Chyuedu/leetcode_study

1id,slug,title,difficulty,tags,category21,two-sum,Two Sum,Easy,Array;Hash Table,Array32,add-two-numbers,Add Two Numbers,Medium,Linked List;Math;Recursion,Linked List43,longest-substring-without-repeating-characters,Longest Substring Without Repeating Characters,Medium,Hash Table;String;Sliding Window,Hash Table54,median-of-two-sorted-arrays,Median of Two Sorted Arrays,Hard,Array;Binary Search;Divide and Conquer,Array65,longest-palindromic-substring,Longest Palindromic Substring,Medium,Two Pointers;String;Dynamic Programming,Two Pointers76,zigzag-conversion,Zigzag Conversion,Medium,String,String87,reverse-integer,Reverse Integer,Medium,Math,Math98,string-to-integer-atoi,String to Integer (atoi),Medium,String,String109,palindrome-number,Palindrome Number,Easy,Math,Math1110,regular-expression-matching,Regular Expression Matching,Hard,String;Dynamic Programming;Recursion,String1211,container-with-most-water,Container With Most Water,Medium,Array;Two Pointers;Greedy,Array1312,integer-to-roman,Integer to Roman,Medium,Hash Table;Math;String,Hash Table1413,roman-to-integer,Roman to Integer,Easy,Hash Table;Math;String,Hash Table1514,longest-common-prefix,Longest Common Prefix,Easy,Array;String;Trie,Array1615,3sum,3Sum,Medium,Array;Two Pointers;Sorting,Array1716,3sum-closest,3Sum Closest,Medium,Array;Two Pointers;Sorting,Array1817,letter-combinations-of-a-phone-number,Letter Combinations of a Phone Number,Medium,Hash Table;String;Backtracking,Hash Table1918,4sum,4Sum,Medium,Array;Two Pointers;Sorting,Array2019,remove-nth-node-from-end-of-list,Remove Nth Node From End of List,Medium,Linked List;Two Pointers,Linked List2120,valid-parentheses,Valid Parentheses,Easy,String;Stack,String2221,merge-two-sorted-lists,Merge Two Sorted Lists,Easy,Linked List;Recursion,Linked List2322,generate-parentheses,Generate Parentheses,Medium,String;Dynamic Programming;Backtracking,String2423,merge-k-sorted-lists,Merge k Sorted Lists,Hard,Linked List;Divide and Conquer;Heap (Priority Queue);Merge Sort,Linked List2524,swap-nodes-in-pairs,Swap Nodes in Pairs,Medium,Linked List;Recursion,Linked List2625,reverse-nodes-in-k-group,Reverse Nodes in k-Group,Hard,Linked List;Recursion,Linked List2726,remove-duplicates-from-sorted-array,Remove Duplicates from Sorted Array,Easy,Array;Two Pointers,Array2827,remove-element,Remove Element,Easy,Array;Two Pointers,Array2928,find-the-index-of-the-first-occurrence-in-a-string,Find the Index of the First Occurrence in a String,Easy,Two Pointers;String;String Matching,Two Pointers3029,divide-two-integers,Divide Two Integers,Medium,Math;Bit Manipulation,Math3130,substring-with-concatenation-of-all-words,Substring with Concatenation of All Words,Hard,Hash Table;String;Sliding Window,Hash Table3231,next-permutation,Next Permutation,Medium,Array;Two Pointers,Array3332,longest-valid-parentheses,Longest Valid Parentheses,Hard,String;Dynamic Programming;Stack,String3433,search-in-rotated-sorted-array,Search in Rotated Sorted Array,Medium,Array;Binary Search,Array3534,find-first-and-last-position-of-element-in-sorted-array,Find First and Last Position of Element in Sorted Array,Medium,Array;Binary Search,Array3635,search-insert-position,Search Insert Position,Easy,Array;Binary Search,Array3736,valid-sudoku,Valid Sudoku,Medium,Array;Hash Table;Matrix,Array3837,sudoku-solver,Sudoku Solver,Hard,Array;Hash Table;Backtracking;Matrix,Array3938,count-and-say,Count and Say,Medium,String,String4039,combination-sum,Combination Sum,Medium,Array;Backtracking,Array4140,combination-sum-ii,Combination Sum II,Medium,Array;Backtracking,Array4241,first-missing-positive,First Missing Positive,Hard,Array;Hash Table,Array4342,trapping-rain-water,Trapping Rain Water,Hard,Array;Two Pointers;Dynamic Programming;Stack;Monotonic Stack,Array4443,multiply-strings,Multiply Strings,Medium,Math;String;Simulation,Math4544,wildcard-matching,Wildcard Matching,Hard,String;Dynamic Programming;Greedy;Recursion,String4645,jump-game-ii,Jump Game II,Medium,Array;Dynamic Programming;Greedy,Array4746,permutations,Permutations,Medium,Array;Backtracking,Array4847,permutations-ii,Permutations II,Medium,Array;Backtracking;Sorting,Array4948,rotate-image,Rotate Image,Medium,Array;Math;Matrix,Array5049,group-anagrams,Group Anagrams,Medium,Array;Hash Table;String;Sorting,Array5150,powx-n,"Pow(x, n)",Medium,Math;Recursion,Math5251,n-queens,N-Queens,Hard,Array;Backtracking,Array5352,n-queens-ii,N-Queens II,Hard,Backtracking,Backtracking5453,maximum-subarray,Maximum Subarray,Medium,Array;Divide and Conquer;Dynamic Programming,Array5554,spiral-matrix,Spiral Matrix,Medium,Array;Matrix;Simulation,Array5655,jump-game,Jump Game,Medium,Array;Dynamic Programming;Greedy,Array5756,merge-intervals,Merge Intervals,Medium,Array;Sorting,Array5857,insert-interval,Insert Interval,Medium,Array,Array5958,length-of-last-word,Length of Last Word,Easy,String,String6059,spiral-matrix-ii,Spiral Matrix II,Medium,Array;Matrix;Simulation,Array6160,permutation-sequence,Permutation Sequence,Hard,Math;Recursion,Math6261,rotate-list,Rotate List,Medium,Linked List;Two Pointers,Linked List6362,unique-paths,Unique Paths,Medium,Math;Dynamic Programming;Combinatorics,Math6463,unique-paths-ii,Unique Paths II,Medium,Array;Dynamic Programming;Matrix,Array6564,minimum-path-sum,Minimum Path Sum,Medium,Array;Dynamic Programming;Matrix,Array6665,valid-number,Valid Number,Hard,String,String6766,plus-one,Plus One,Easy,Array;Math,Array6867,add-binary,Add Binary,Easy,Math;String;Bit Manipulation;Simulation,Math6968,text-justification,Text Justification,Hard,Array;String;Simulation,Array7069,sqrtx,Sqrt(x),Easy,Math;Binary Search,Math7170,climbing-stairs,Climbing Stairs,Easy,Math;Dynamic Programming;Memoization,Math7271,simplify-path,Simplify Path,Medium,String;Stack,String7372,edit-distance,Edit Distance,Medium,String;Dynamic Programming,String7473,set-matrix-zeroes,Set Matrix Zeroes,Medium,Array;Hash Table;Matrix,Array7574,search-a-2d-matrix,Search a 2D Matrix,Medium,Array;Binary Search;Matrix,Array7675,sort-colors,Sort Colors,Medium,Array;Two Pointers;Sorting,Array7776,minimum-window-substring,Minimum Window Substring,Hard,Hash Table;String;Sliding Window,Hash Table7877,combinations,Combinations,Medium,Backtracking,Backtracking7978,subsets,Subsets,Medium,Array;Backtracking;Bit Manipulation,Array8079,word-search,Word Search,Medium,Array;String;Backtracking;Depth-First Search;Matrix,Array8180,remove-duplicates-from-sorted-array-ii,Remove Duplicates from Sorted Array II,Medium,Array;Two Pointers,Array8281,search-in-rotated-sorted-array-ii,Search in Rotated Sorted Array II,Medium,Array;Binary Search,Array8382,remove-duplicates-from-sorted-list-ii,Remove Duplicates from Sorted List II,Medium,Linked List;Two Pointers,Linked List8483,remove-duplicates-from-sorted-list,Remove Duplicates from Sorted List,Easy,Linked List,Linked List8584,largest-rectangle-in-histogram,Largest Rectangle in Histogram,Hard,Array;Stack;Monotonic Stack,Array8685,maximal-rectangle,Maximal Rectangle,Hard,Array;Dynamic Programming;Stack;Matrix;Monotonic Stack,Array8786,partition-list,Partition List,Medium,Linked List;Two Pointers,Linked List8887,scramble-string,Scramble String,Hard,String;Dynamic Programming,String8988,merge-sorted-array,Merge Sorted Array,Easy,Array;Two Pointers;Sorting,Array9089,gray-code,Gray Code,Medium,Math;Backtracking;Bit Manipulation,Math9190,subsets-ii,Subsets II,Medium,Array;Backtracking;Bit Manipulation,Array9291,decode-ways,Decode Ways,Medium,String;Dynamic Programming,String9392,reverse-linked-list-ii,Reverse Linked List II,Medium,Linked List,Linked List9493,restore-ip-addresses,Restore IP Addresses,Medium,String;Backtracking,String9594,binary-tree-inorder-traversal,Binary Tree Inorder Traversal,Easy,Stack;Tree;Depth-First Search;Binary Tree,Stack9695,unique-binary-search-trees-ii,Unique Binary Search Trees II,Medium,Dynamic Programming;Backtracking;Tree;Binary Search Tree;Binary Tree,Dynamic Programming9796,unique-binary-search-trees,Unique Binary Search Trees,Medium,Math;Dynamic Programming;Tree;Binary Search Tree;Binary Tree,Math9897,interleaving-string,Interleaving String,Medium,String;Dynamic Programming,String9998,validate-binary-search-tree,Validate Binary Search Tree,Medium,Tree;Depth-First Search;Binary Search Tree;Binary Tree,Tree10099,recover-binary-search-tree,Recover Binary Search Tree,Medium,Tree;Depth-First Search;Binary Search Tree;Binary Tree,Tree101100,same-tree,Same Tree,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree102101,symmetric-tree,Symmetric Tree,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree103102,binary-tree-level-order-traversal,Binary Tree Level Order Traversal,Medium,Tree;Breadth-First Search;Binary Tree,Tree104103,binary-tree-zigzag-level-order-traversal,Binary Tree Zigzag Level Order Traversal,Medium,Tree;Breadth-First Search;Binary Tree,Tree105104,maximum-depth-of-binary-tree,Maximum Depth of Binary Tree,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree106105,construct-binary-tree-from-preorder-and-inorder-traversal,Construct Binary Tree from Preorder and Inorder Traversal,Medium,Array;Hash Table;Divide and Conquer;Tree;Binary Tree,Array107106,construct-binary-tree-from-inorder-and-postorder-traversal,Construct Binary Tree from Inorder and Postorder Traversal,Medium,Array;Hash Table;Divide and Conquer;Tree;Binary Tree,Array108107,binary-tree-level-order-traversal-ii,Binary Tree Level Order Traversal II,Medium,Tree;Breadth-First Search;Binary Tree,Tree109108,convert-sorted-array-to-binary-search-tree,Convert Sorted Array to Binary Search Tree,Easy,Array;Divide and Conquer;Tree;Binary Search Tree;Binary Tree,Array110109,convert-sorted-list-to-binary-search-tree,Convert Sorted List to Binary Search Tree,Medium,Linked List;Divide and Conquer;Tree;Binary Search Tree;Binary Tree,Linked List111110,balanced-binary-tree,Balanced Binary Tree,Easy,Tree;Depth-First Search;Binary Tree,Tree112111,minimum-depth-of-binary-tree,Minimum Depth of Binary Tree,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree113112,path-sum,Path Sum,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree114113,path-sum-ii,Path Sum II,Medium,Backtracking;Tree;Depth-First Search;Binary Tree,Backtracking115114,flatten-binary-tree-to-linked-list,Flatten Binary Tree to Linked List,Medium,Linked List;Stack;Tree;Depth-First Search;Binary Tree,Linked List116115,distinct-subsequences,Distinct Subsequences,Hard,String;Dynamic Programming,String117116,populating-next-right-pointers-in-each-node,Populating Next Right Pointers in Each Node,Medium,Linked List;Tree;Depth-First Search;Breadth-First Search;Binary Tree,Linked List118117,populating-next-right-pointers-in-each-node-ii,Populating Next Right Pointers in Each Node II,Medium,Linked List;Tree;Depth-First Search;Breadth-First Search;Binary Tree,Linked List119118,pascals-triangle,Pascal's Triangle,Easy,Array;Dynamic Programming,Array120119,pascals-triangle-ii,Pascal's Triangle II,Easy,Array;Dynamic Programming,Array121120,triangle,Triangle,Medium,Array;Dynamic Programming,Array122121,best-time-to-buy-and-sell-stock,Best Time to Buy and Sell Stock,Easy,Array;Dynamic Programming,Array123122,best-time-to-buy-and-sell-stock-ii,Best Time to Buy and Sell Stock II,Medium,Array;Dynamic Programming;Greedy,Array124123,best-time-to-buy-and-sell-stock-iii,Best Time to Buy and Sell Stock III,Hard,Array;Dynamic Programming,Array125124,binary-tree-maximum-path-sum,Binary Tree Maximum Path Sum,Hard,Dynamic Programming;Tree;Depth-First Search;Binary Tree,Dynamic Programming126125,valid-palindrome,Valid Palindrome,Easy,Two Pointers;String,Two Pointers127126,word-ladder-ii,Word Ladder II,Hard,Hash Table;String;Backtracking;Breadth-First Search,Hash Table128127,word-ladder,Word Ladder,Hard,Hash Table;String;Breadth-First Search,Hash Table129128,longest-consecutive-sequence,Longest Consecutive Sequence,Medium,Array;Hash Table;Union-Find,Array130129,sum-root-to-leaf-numbers,Sum Root to Leaf Numbers,Medium,Tree;Depth-First Search;Binary Tree,Tree131130,surrounded-regions,Surrounded Regions,Medium,Array;Depth-First Search;Breadth-First Search;Union-Find;Matrix,Array132131,palindrome-partitioning,Palindrome Partitioning,Medium,String;Dynamic Programming;Backtracking,String133132,palindrome-partitioning-ii,Palindrome Partitioning II,Hard,String;Dynamic Programming,String134133,clone-graph,Clone Graph,Medium,Hash Table;Depth-First Search;Breadth-First Search;Graph Theory,Hash Table135134,gas-station,Gas Station,Medium,Array;Greedy,Array136135,candy,Candy,Hard,Array;Greedy,Array137136,single-number,Single Number,Easy,Array;Bit Manipulation,Array138137,single-number-ii,Single Number II,Medium,Array;Bit Manipulation,Array139138,copy-list-with-random-pointer,Copy List with Random Pointer,Medium,Hash Table;Linked List,Hash Table140139,word-break,Word Break,Medium,Array;Hash Table;String;Dynamic Programming;Trie;Memoization,Array141140,word-break-ii,Word Break II,Hard,Array;Hash Table;String;Dynamic Programming;Backtracking;Trie;Memoization,Array142141,linked-list-cycle,Linked List Cycle,Easy,Hash Table;Linked List;Two Pointers,Hash Table143142,linked-list-cycle-ii,Linked List Cycle II,Medium,Hash Table;Linked List;Two Pointers,Hash Table144143,reorder-list,Reorder List,Medium,Linked List;Two Pointers;Stack;Recursion,Linked List145144,binary-tree-preorder-traversal,Binary Tree Preorder Traversal,Easy,Stack;Tree;Depth-First Search;Binary Tree,Stack146145,binary-tree-postorder-traversal,Binary Tree Postorder Traversal,Easy,Stack;Tree;Depth-First Search;Binary Tree,Stack147146,lru-cache,LRU Cache,Medium,Hash Table;Linked List;Design;Doubly-Linked List,Hash Table148147,insertion-sort-list,Insertion Sort List,Medium,Linked List;Sorting,Linked List149148,sort-list,Sort List,Medium,Linked List;Two Pointers;Divide and Conquer;Sorting;Merge Sort,Linked List150149,max-points-on-a-line,Max Points on a Line,Hard,Array;Hash Table;Math;Geometry,Array151150,evaluate-reverse-polish-notation,Evaluate Reverse Polish Notation,Medium,Array;Math;Stack,Array152151,reverse-words-in-a-string,Reverse Words in a String,Medium,Two Pointers;String,Two Pointers153152,maximum-product-subarray,Maximum Product Subarray,Medium,Array;Dynamic Programming,Array154153,find-minimum-in-rotated-sorted-array,Find Minimum in Rotated Sorted Array,Medium,Array;Binary Search,Array155154,find-minimum-in-rotated-sorted-array-ii,Find Minimum in Rotated Sorted Array II,Hard,Array;Binary Search,Array156155,min-stack,Min Stack,Medium,Stack;Design,Stack157156,binary-tree-upside-down,Binary Tree Upside Down,Medium,Tree;Depth-First Search;Binary Tree,Tree158157,read-n-characters-given-read4,Read N Characters Given Read4,Easy,Array;Simulation;Interactive,Array159158,read-n-characters-given-read4-ii-call-multiple-times,Read N Characters Given read4 II - Call Multiple Times,Hard,Array;Simulation;Interactive,Array160159,longest-substring-with-at-most-two-distinct-characters,Longest Substring with At Most Two Distinct Characters,Medium,Hash Table;String;Sliding Window,Hash Table161160,intersection-of-two-linked-lists,Intersection of Two Linked Lists,Easy,Hash Table;Linked List;Two Pointers,Hash Table162161,one-edit-distance,One Edit Distance,Medium,Two Pointers;String,Two Pointers163162,find-peak-element,Find Peak Element,Medium,Array;Binary Search,Array164163,missing-ranges,Missing Ranges,Easy,Array,Array165164,maximum-gap,Maximum Gap,Medium,Array;Sorting;Bucket Sort;Radix Sort,Array166165,compare-version-numbers,Compare Version Numbers,Medium,Two Pointers;String,Two Pointers167166,fraction-to-recurring-decimal,Fraction to Recurring Decimal,Medium,Hash Table;Math;String,Hash Table168167,two-sum-ii-input-array-is-sorted,Two Sum II - Input Array Is Sorted,Medium,Array;Two Pointers;Binary Search,Array169168,excel-sheet-column-title,Excel Sheet Column Title,Easy,Math;String,Math170169,majority-element,Majority Element,Easy,Array;Hash Table;Divide and Conquer;Sorting;Counting,Array171170,two-sum-iii-data-structure-design,Two Sum III - Data structure design,Easy,Array;Hash Table;Two Pointers;Design;Data Stream,Array172171,excel-sheet-column-number,Excel Sheet Column Number,Easy,Math;String,Math173172,factorial-trailing-zeroes,Factorial Trailing Zeroes,Medium,Math,Math174173,binary-search-tree-iterator,Binary Search Tree Iterator,Medium,Stack;Tree;Design;Binary Search Tree;Binary Tree;Iterator,Stack175174,dungeon-game,Dungeon Game,Hard,Array;Dynamic Programming;Matrix,Array176175,combine-two-tables,Combine Two Tables,Easy,Database,Database177176,second-highest-salary,Second Highest Salary,Medium,Database,Database178177,nth-highest-salary,Nth Highest Salary,Medium,Database,Database179178,rank-scores,Rank Scores,Medium,Database,Database180179,largest-number,Largest Number,Medium,Array;String;Greedy;Sorting,Array181180,consecutive-numbers,Consecutive Numbers,Medium,Database,Database182181,employees-earning-more-than-their-managers,Employees Earning More Than Their Managers,Easy,Database,Database183182,duplicate-emails,Duplicate Emails,Easy,Database,Database184183,customers-who-never-order,Customers Who Never Order,Easy,Database,Database185184,department-highest-salary,Department Highest Salary,Medium,Database,Database186185,department-top-three-salaries,Department Top Three Salaries,Hard,Database,Database187186,reverse-words-in-a-string-ii,Reverse Words in a String II,Medium,Two Pointers;String,Two Pointers188187,repeated-dna-sequences,Repeated DNA Sequences,Medium,Hash Table;String;Bit Manipulation;Sliding Window;Rolling Hash;Hash Function,Hash Table189188,best-time-to-buy-and-sell-stock-iv,Best Time to Buy and Sell Stock IV,Hard,Array;Dynamic Programming,Array190189,rotate-array,Rotate Array,Medium,Array;Math;Two Pointers,Array191190,reverse-bits,Reverse Bits,Easy,Divide and Conquer;Bit Manipulation,Divide and Conquer192191,number-of-1-bits,Number of 1 Bits,Easy,Divide and Conquer;Bit Manipulation,Divide and Conquer193192,word-frequency,Word Frequency,Medium,Shell,Shell194193,valid-phone-numbers,Valid Phone Numbers,Easy,Shell,Shell195194,transpose-file,Transpose File,Medium,Shell,Shell196195,tenth-line,Tenth Line,Easy,Shell,Shell197196,delete-duplicate-emails,Delete Duplicate Emails,Easy,Database,Database198197,rising-temperature,Rising Temperature,Easy,Database,Database199198,house-robber,House Robber,Medium,Array;Dynamic Programming,Array200199,binary-tree-right-side-view,Binary Tree Right Side View,Medium,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree201200,number-of-islands,Number of Islands,Medium,Array;Depth-First Search;Breadth-First Search;Union-Find;Matrix,Array202201,bitwise-and-of-numbers-range,Bitwise AND of Numbers Range,Medium,Bit Manipulation,Bit Manipulation203202,happy-number,Happy Number,Easy,Hash Table;Math;Two Pointers,Hash Table204203,remove-linked-list-elements,Remove Linked List Elements,Easy,Linked List;Recursion,Linked List205204,count-primes,Count Primes,Medium,Array;Math;Enumeration;Number Theory,Array206205,isomorphic-strings,Isomorphic Strings,Easy,Hash Table;String,Hash Table207206,reverse-linked-list,Reverse Linked List,Easy,Linked List;Recursion,Linked List208207,course-schedule,Course Schedule,Medium,Depth-First Search;Breadth-First Search;Graph Theory;Topological Sort,Depth-First Search209208,implement-trie-prefix-tree,Implement Trie (Prefix Tree),Medium,Hash Table;String;Design;Trie,Hash Table210209,minimum-size-subarray-sum,Minimum Size Subarray Sum,Medium,Array;Binary Search;Sliding Window;Prefix Sum,Array211210,course-schedule-ii,Course Schedule II,Medium,Depth-First Search;Breadth-First Search;Graph Theory;Topological Sort,Depth-First Search212211,design-add-and-search-words-data-structure,Design Add and Search Words Data Structure,Medium,String;Depth-First Search;Design;Trie,String213212,word-search-ii,Word Search II,Hard,Array;String;Backtracking;Trie;Matrix,Array214213,house-robber-ii,House Robber II,Medium,Array;Dynamic Programming,Array215214,shortest-palindrome,Shortest Palindrome,Hard,String;Rolling Hash;String Matching;Hash Function,String216215,kth-largest-element-in-an-array,Kth Largest Element in an Array,Medium,Array;Divide and Conquer;Sorting;Heap (Priority Queue);Quickselect,Array217216,combination-sum-iii,Combination Sum III,Medium,Array;Backtracking,Array218217,contains-duplicate,Contains Duplicate,Easy,Array;Hash Table;Sorting,Array219218,the-skyline-problem,The Skyline Problem,Hard,Array;Divide and Conquer;Binary Indexed Tree;Segment Tree;Sweep Line;Sorting;Heap (Priority Queue);Ordered Set,Array220219,contains-duplicate-ii,Contains Duplicate II,Easy,Array;Hash Table;Sliding Window,Array221220,contains-duplicate-iii,Contains Duplicate III,Hard,Array;Sliding Window;Sorting;Bucket Sort;Ordered Set,Array222221,maximal-square,Maximal Square,Medium,Array;Dynamic Programming;Matrix,Array223222,count-complete-tree-nodes,Count Complete Tree Nodes,Easy,Binary Search;Bit Manipulation;Tree;Binary Tree,Binary Search224223,rectangle-area,Rectangle Area,Medium,Math;Geometry,Math225224,basic-calculator,Basic Calculator,Hard,Math;String;Stack;Recursion,Math226225,implement-stack-using-queues,Implement Stack using Queues,Easy,Stack;Design;Queue,Stack227226,invert-binary-tree,Invert Binary Tree,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree228227,basic-calculator-ii,Basic Calculator II,Medium,Math;String;Stack,Math229228,summary-ranges,Summary Ranges,Easy,Array,Array230229,majority-element-ii,Majority Element II,Medium,Array;Hash Table;Sorting;Counting,Array231230,kth-smallest-element-in-a-bst,Kth Smallest Element in a BST,Medium,Tree;Depth-First Search;Binary Search Tree;Binary Tree,Tree232231,power-of-two,Power of Two,Easy,Math;Bit Manipulation;Recursion,Math233232,implement-queue-using-stacks,Implement Queue using Stacks,Easy,Stack;Design;Queue,Stack234233,number-of-digit-one,Number of Digit One,Hard,Math;Dynamic Programming;Recursion,Math235234,palindrome-linked-list,Palindrome Linked List,Easy,Linked List;Two Pointers;Stack;Recursion,Linked List236235,lowest-common-ancestor-of-a-binary-search-tree,Lowest Common Ancestor of a Binary Search Tree,Medium,Tree;Depth-First Search;Binary Search Tree;Binary Tree,Tree237236,lowest-common-ancestor-of-a-binary-tree,Lowest Common Ancestor of a Binary Tree,Medium,Tree;Depth-First Search;Binary Tree,Tree238237,delete-node-in-a-linked-list,Delete Node in a Linked List,Medium,Linked List,Linked List239238,product-of-array-except-self,Product of Array Except Self,Medium,Array;Prefix Sum,Array240239,sliding-window-maximum,Sliding Window Maximum,Hard,Array;Queue;Sliding Window;Heap (Priority Queue);Monotonic Queue,Array241240,search-a-2d-matrix-ii,Search a 2D Matrix II,Medium,Array;Binary Search;Divide and Conquer;Matrix,Array242241,different-ways-to-add-parentheses,Different Ways to Add Parentheses,Medium,Math;String;Dynamic Programming;Recursion;Memoization,Math243242,valid-anagram,Valid Anagram,Easy,Hash Table;String;Sorting,Hash Table244243,shortest-word-distance,Shortest Word Distance,Easy,Array;String,Array245244,shortest-word-distance-ii,Shortest Word Distance II,Medium,Array;Hash Table;Two Pointers;String;Design,Array246245,shortest-word-distance-iii,Shortest Word Distance III,Medium,Array;String,Array247246,strobogrammatic-number,Strobogrammatic Number,Easy,Hash Table;Two Pointers;String,Hash Table248247,strobogrammatic-number-ii,Strobogrammatic Number II,Medium,Array;String;Recursion,Array249248,strobogrammatic-number-iii,Strobogrammatic Number III,Hard,Array;String;Recursion,Array250249,group-shifted-strings,Group Shifted Strings,Medium,Array;Hash Table;String,Array251250,count-univalue-subtrees,Count Univalue Subtrees,Medium,Tree;Depth-First Search;Binary Tree,Tree252251,flatten-2d-vector,Flatten 2D Vector,Medium,Array;Two Pointers;Design;Iterator,Array253252,meeting-rooms,Meeting Rooms,Easy,Array;Sorting,Array254253,meeting-rooms-ii,Meeting Rooms II,Medium,Array;Two Pointers;Greedy;Sorting;Heap (Priority Queue);Prefix Sum,Array255254,factor-combinations,Factor Combinations,Medium,Backtracking,Backtracking256255,verify-preorder-sequence-in-binary-search-tree,Verify Preorder Sequence in Binary Search Tree,Medium,Array;Stack;Tree;Binary Search Tree;Recursion;Monotonic Stack;Binary Tree,Array257256,paint-house,Paint House,Medium,Array;Dynamic Programming,Array258257,binary-tree-paths,Binary Tree Paths,Easy,String;Backtracking;Tree;Depth-First Search;Binary Tree,String259258,add-digits,Add Digits,Easy,Math;Simulation;Number Theory,Math260259,3sum-smaller,3Sum Smaller,Medium,Array;Two Pointers;Binary Search;Sorting,Array261260,single-number-iii,Single Number III,Medium,Array;Bit Manipulation,Array262261,graph-valid-tree,Graph Valid Tree,Medium,Depth-First Search;Breadth-First Search;Union-Find;Graph Theory,Depth-First Search263262,trips-and-users,Trips and Users,Hard,Database,Database264263,ugly-number,Ugly Number,Easy,Math,Math265264,ugly-number-ii,Ugly Number II,Medium,Hash Table;Math;Dynamic Programming;Heap (Priority Queue),Hash Table266265,paint-house-ii,Paint House II,Hard,Array;Dynamic Programming,Array267266,palindrome-permutation,Palindrome Permutation,Easy,Hash Table;String;Bit Manipulation,Hash Table268267,palindrome-permutation-ii,Palindrome Permutation II,Medium,Hash Table;String;Backtracking,Hash Table269268,missing-number,Missing Number,Easy,Array;Hash Table;Math;Binary Search;Bit Manipulation;Sorting,Array270269,alien-dictionary,Alien Dictionary,Hard,Array;String;Depth-First Search;Breadth-First Search;Graph Theory;Topological Sort,Array271270,closest-binary-search-tree-value,Closest Binary Search Tree Value,Easy,Binary Search;Tree;Depth-First Search;Binary Search Tree;Binary Tree,Binary Search272271,encode-and-decode-strings,Encode and Decode Strings,Medium,Array;String;Design,Array273272,closest-binary-search-tree-value-ii,Closest Binary Search Tree Value II,Hard,Two Pointers;Stack;Tree;Depth-First Search;Binary Search Tree;Heap (Priority Queue);Binary Tree,Two Pointers274273,integer-to-english-words,Integer to English Words,Hard,Math;String;Recursion,Math275274,h-index,H-Index,Medium,Array;Sorting;Counting Sort,Array276275,h-index-ii,H-Index II,Medium,Array;Binary Search,Array277276,paint-fence,Paint Fence,Medium,Dynamic Programming,Dynamic Programming278277,find-the-celebrity,Find the Celebrity,Medium,Two Pointers;Graph Theory;Interactive,Two Pointers279278,first-bad-version,First Bad Version,Easy,Binary Search;Interactive,Binary Search280279,perfect-squares,Perfect Squares,Medium,Math;Dynamic Programming;Breadth-First Search,Math281280,wiggle-sort,Wiggle Sort,Medium,Array;Greedy;Sorting,Array282281,zigzag-iterator,Zigzag Iterator,Medium,Array;Design;Queue;Iterator,Array283282,expression-add-operators,Expression Add Operators,Hard,Math;String;Backtracking,Math284283,move-zeroes,Move Zeroes,Easy,Array;Two Pointers,Array285284,peeking-iterator,Peeking Iterator,Medium,Array;Design;Iterator,Array286285,inorder-successor-in-bst,Inorder Successor in BST,Medium,Tree;Depth-First Search;Binary Search Tree;Binary Tree,Tree287286,walls-and-gates,Walls and Gates,Medium,Array;Breadth-First Search;Matrix,Array288287,find-the-duplicate-number,Find the Duplicate Number,Medium,Array;Two Pointers;Binary Search;Bit Manipulation,Array289288,unique-word-abbreviation,Unique Word Abbreviation,Medium,Array;Hash Table;String;Design,Array290289,game-of-life,Game of Life,Medium,Array;Matrix;Simulation,Array291290,word-pattern,Word Pattern,Easy,Hash Table;String,Hash Table292291,word-pattern-ii,Word Pattern II,Medium,Hash Table;String;Backtracking,Hash Table293292,nim-game,Nim Game,Easy,Math;Brainteaser;Game Theory,Math294293,flip-game,Flip Game,Easy,String,String295294,flip-game-ii,Flip Game II,Medium,Math;Dynamic Programming;Backtracking;Memoization;Game Theory,Math296295,find-median-from-data-stream,Find Median from Data Stream,Hard,Two Pointers;Design;Sorting;Heap (Priority Queue);Data Stream,Two Pointers297296,best-meeting-point,Best Meeting Point,Hard,Array;Math;Sorting;Matrix,Array298297,serialize-and-deserialize-binary-tree,Serialize and Deserialize Binary Tree,Hard,String;Tree;Depth-First Search;Breadth-First Search;Design;Binary Tree,String299298,binary-tree-longest-consecutive-sequence,Binary Tree Longest Consecutive Sequence,Medium,Tree;Depth-First Search;Binary Tree,Tree300299,bulls-and-cows,Bulls and Cows,Medium,Hash Table;String;Counting,Hash Table301300,longest-increasing-subsequence,Longest Increasing Subsequence,Medium,Array;Binary Search;Dynamic Programming,Array302301,remove-invalid-parentheses,Remove Invalid Parentheses,Hard,String;Backtracking;Breadth-First Search,String303302,smallest-rectangle-enclosing-black-pixels,Smallest Rectangle Enclosing Black Pixels,Hard,Array;Binary Search;Depth-First Search;Breadth-First Search;Matrix,Array304303,range-sum-query-immutable,Range Sum Query - Immutable,Easy,Array;Design;Prefix Sum,Array305304,range-sum-query-2d-immutable,Range Sum Query 2D - Immutable,Medium,Array;Design;Matrix;Prefix Sum,Array306305,number-of-islands-ii,Number of Islands II,Hard,Array;Hash Table;Union-Find,Array307306,additive-number,Additive Number,Medium,String;Backtracking,String308307,range-sum-query-mutable,Range Sum Query - Mutable,Medium,Array;Divide and Conquer;Design;Binary Indexed Tree;Segment Tree,Array309308,range-sum-query-2d-mutable,Range Sum Query 2D - Mutable,Medium,Array;Design;Binary Indexed Tree;Segment Tree;Matrix,Array310309,best-time-to-buy-and-sell-stock-with-cooldown,Best Time to Buy and Sell Stock with Cooldown,Medium,Array;Dynamic Programming,Array311310,minimum-height-trees,Minimum Height Trees,Medium,Depth-First Search;Breadth-First Search;Graph Theory;Topological Sort,Depth-First Search312311,sparse-matrix-multiplication,Sparse Matrix Multiplication,Medium,Array;Hash Table;Matrix,Array313312,burst-balloons,Burst Balloons,Hard,Array;Dynamic Programming,Array314313,super-ugly-number,Super Ugly Number,Medium,Array;Math;Dynamic Programming,Array315314,binary-tree-vertical-order-traversal,Binary Tree Vertical Order Traversal,Medium,Hash Table;Tree;Depth-First Search;Breadth-First Search;Sorting;Binary Tree,Hash Table316315,count-of-smaller-numbers-after-self,Count of Smaller Numbers After Self,Hard,Array;Binary Search;Divide and Conquer;Binary Indexed Tree;Segment Tree;Merge Sort;Ordered Set,Array317316,remove-duplicate-letters,Remove Duplicate Letters,Medium,String;Stack;Greedy;Monotonic Stack,String318317,shortest-distance-from-all-buildings,Shortest Distance from All Buildings,Hard,Array;Breadth-First Search;Matrix,Array319318,maximum-product-of-word-lengths,Maximum Product of Word Lengths,Medium,Array;String;Bit Manipulation,Array320319,bulb-switcher,Bulb Switcher,Medium,Math;Brainteaser,Math321320,generalized-abbreviation,Generalized Abbreviation,Medium,String;Backtracking;Bit Manipulation,String322321,create-maximum-number,Create Maximum Number,Hard,Array;Two Pointers;Stack;Greedy;Monotonic Stack,Array323322,coin-change,Coin Change,Medium,Array;Dynamic Programming;Breadth-First Search,Array324323,number-of-connected-components-in-an-undirected-graph,Number of Connected Components in an Undirected Graph,Medium,Depth-First Search;Breadth-First Search;Union-Find;Graph Theory,Depth-First Search325324,wiggle-sort-ii,Wiggle Sort II,Medium,Array;Divide and Conquer;Greedy;Sorting;Quickselect,Array326325,maximum-size-subarray-sum-equals-k,Maximum Size Subarray Sum Equals k,Medium,Array;Hash Table;Prefix Sum,Array327326,power-of-three,Power of Three,Easy,Math;Recursion,Math328327,count-of-range-sum,Count of Range Sum,Hard,Array;Binary Search;Divide and Conquer;Binary Indexed Tree;Segment Tree;Merge Sort;Ordered Set,Array329328,odd-even-linked-list,Odd Even Linked List,Medium,Linked List,Linked List330329,longest-increasing-path-in-a-matrix,Longest Increasing Path in a Matrix,Hard,Array;Dynamic Programming;Depth-First Search;Breadth-First Search;Graph Theory;Topological Sort;Memoization;Matrix,Array331330,patching-array,Patching Array,Hard,Array;Greedy,Array332331,verify-preorder-serialization-of-a-binary-tree,Verify Preorder Serialization of a Binary Tree,Medium,String;Stack;Tree;Binary Tree,String333332,reconstruct-itinerary,Reconstruct Itinerary,Hard,Array;String;Depth-First Search;Graph Theory;Sorting;Heap (Priority Queue);Eulerian Circuit,Array334333,largest-bst-subtree,Largest BST Subtree,Medium,Dynamic Programming;Tree;Depth-First Search;Binary Search Tree;Binary Tree,Dynamic Programming335334,increasing-triplet-subsequence,Increasing Triplet Subsequence,Medium,Array;Greedy,Array336335,self-crossing,Self Crossing,Hard,Array;Math;Geometry,Array337336,palindrome-pairs,Palindrome Pairs,Hard,Array;Hash Table;String;Trie;Hash Function,Array338337,house-robber-iii,House Robber III,Medium,Dynamic Programming;Tree;Depth-First Search;Binary Tree,Dynamic Programming339338,counting-bits,Counting Bits,Easy,Dynamic Programming;Bit Manipulation,Dynamic Programming340339,nested-list-weight-sum,Nested List Weight Sum,Medium,Depth-First Search;Breadth-First Search,Depth-First Search341340,longest-substring-with-at-most-k-distinct-characters,Longest Substring with At Most K Distinct Characters,Medium,Hash Table;String;Sliding Window,Hash Table342341,flatten-nested-list-iterator,Flatten Nested List Iterator,Medium,Stack;Tree;Depth-First Search;Design;Queue;Iterator,Stack343342,power-of-four,Power of Four,Easy,Math;Bit Manipulation;Recursion,Math344343,integer-break,Integer Break,Medium,Math;Dynamic Programming,Math345344,reverse-string,Reverse String,Easy,Two Pointers;String,Two Pointers346345,reverse-vowels-of-a-string,Reverse Vowels of a String,Easy,Two Pointers;String,Two Pointers347346,moving-average-from-data-stream,Moving Average from Data Stream,Easy,Array;Design;Queue;Data Stream,Array348347,top-k-frequent-elements,Top K Frequent Elements,Medium,Array;Hash Table;Divide and Conquer;Sorting;Heap (Priority Queue);Bucket Sort;Counting;Quickselect,Array349348,design-tic-tac-toe,Design Tic-Tac-Toe,Medium,Array;Hash Table;Design;Matrix;Simulation,Array350349,intersection-of-two-arrays,Intersection of Two Arrays,Easy,Array;Hash Table;Two Pointers;Binary Search;Sorting,Array351350,intersection-of-two-arrays-ii,Intersection of Two Arrays II,Easy,Array;Hash Table;Two Pointers;Binary Search;Sorting,Array352351,android-unlock-patterns,Android Unlock Patterns,Medium,Dynamic Programming;Backtracking;Bit Manipulation;Bitmask,Dynamic Programming353352,data-stream-as-disjoint-intervals,Data Stream as Disjoint Intervals,Hard,Hash Table;Binary Search;Union-Find;Design;Data Stream;Ordered Set,Hash Table354353,design-snake-game,Design Snake Game,Medium,Array;Hash Table;Design;Queue;Simulation,Array355354,russian-doll-envelopes,Russian Doll Envelopes,Hard,Array;Binary Search;Dynamic Programming;Sorting,Array356355,design-twitter,Design Twitter,Medium,Hash Table;Linked List;Design;Heap (Priority Queue),Hash Table357356,line-reflection,Line Reflection,Medium,Array;Hash Table;Math,Array358357,count-numbers-with-unique-digits,Count Numbers with Unique Digits,Medium,Math;Dynamic Programming;Backtracking,Math359358,rearrange-string-k-distance-apart,Rearrange String k Distance Apart,Hard,Hash Table;String;Greedy;Sorting;Heap (Priority Queue);Counting,Hash Table360359,logger-rate-limiter,Logger Rate Limiter,Easy,Hash Table;Design;Data Stream,Hash Table361360,sort-transformed-array,Sort Transformed Array,Medium,Array;Math;Two Pointers;Sorting,Array362361,bomb-enemy,Bomb Enemy,Medium,Array;Dynamic Programming;Matrix,Array363362,design-hit-counter,Design Hit Counter,Medium,Array;Binary Search;Design;Queue;Data Stream,Array364363,max-sum-of-rectangle-no-larger-than-k,Max Sum of Rectangle No Larger Than K,Hard,Array;Binary Search;Matrix;Prefix Sum;Ordered Set,Array365364,nested-list-weight-sum-ii,Nested List Weight Sum II,Medium,Stack;Depth-First Search;Breadth-First Search,Stack366365,water-and-jug-problem,Water and Jug Problem,Medium,Math;Depth-First Search;Breadth-First Search,Math367366,find-leaves-of-binary-tree,Find Leaves of Binary Tree,Medium,Tree;Depth-First Search;Binary Tree,Tree368367,valid-perfect-square,Valid Perfect Square,Easy,Math;Binary Search,Math369368,largest-divisible-subset,Largest Divisible Subset,Medium,Array;Math;Dynamic Programming;Sorting,Array370369,plus-one-linked-list,Plus One Linked List,Medium,Linked List;Math,Linked List371370,range-addition,Range Addition,Medium,Array;Prefix Sum,Array372371,sum-of-two-integers,Sum of Two Integers,Medium,Math;Bit Manipulation,Math373372,super-pow,Super Pow,Medium,Math;Divide and Conquer,Math374373,find-k-pairs-with-smallest-sums,Find K Pairs with Smallest Sums,Medium,Array;Heap (Priority Queue),Array375374,guess-number-higher-or-lower,Guess Number Higher or Lower,Easy,Binary Search;Interactive,Binary Search376375,guess-number-higher-or-lower-ii,Guess Number Higher or Lower II,Medium,Math;Dynamic Programming;Game Theory,Math377376,wiggle-subsequence,Wiggle Subsequence,Medium,Array;Dynamic Programming;Greedy,Array378377,combination-sum-iv,Combination Sum IV,Medium,Array;Dynamic Programming,Array379378,kth-smallest-element-in-a-sorted-matrix,Kth Smallest Element in a Sorted Matrix,Medium,Array;Binary Search;Sorting;Heap (Priority Queue);Matrix,Array380379,design-phone-directory,Design Phone Directory,Medium,Array;Hash Table;Linked List;Design;Queue,Array381380,insert-delete-getrandom-o1,Insert Delete GetRandom O(1),Medium,Array;Hash Table;Math;Design;Randomized,Array382381,insert-delete-getrandom-o1-duplicates-allowed,Insert Delete GetRandom O(1) - Duplicates allowed,Hard,Array;Hash Table;Math;Design;Randomized,Array383382,linked-list-random-node,Linked List Random Node,Medium,Linked List;Math;Reservoir Sampling;Randomized,Linked List384383,ransom-note,Ransom Note,Easy,Hash Table;String;Counting,Hash Table385384,shuffle-an-array,Shuffle an Array,Medium,Array;Math;Design;Randomized,Array386385,mini-parser,Mini Parser,Medium,String;Stack;Depth-First Search,String387386,lexicographical-numbers,Lexicographical Numbers,Medium,Depth-First Search;Trie,Depth-First Search388387,first-unique-character-in-a-string,First Unique Character in a String,Easy,Hash Table;String;Queue;Counting,Hash Table389388,longest-absolute-file-path,Longest Absolute File Path,Medium,String;Stack;Depth-First Search,String390389,find-the-difference,Find the Difference,Easy,Hash Table;String;Bit Manipulation;Sorting,Hash Table391390,elimination-game,Elimination Game,Medium,Math;Recursion,Math392391,perfect-rectangle,Perfect Rectangle,Hard,Array;Hash Table;Math;Geometry;Sweep Line,Array393392,is-subsequence,Is Subsequence,Easy,Two Pointers;String;Dynamic Programming,Two Pointers394393,utf-8-validation,UTF-8 Validation,Medium,Array;Bit Manipulation,Array395394,decode-string,Decode String,Medium,String;Stack;Recursion,String396395,longest-substring-with-at-least-k-repeating-characters,Longest Substring with At Least K Repeating Characters,Medium,Hash Table;String;Divide and Conquer;Sliding Window,Hash Table397396,rotate-function,Rotate Function,Medium,Array;Math;Dynamic Programming,Array398397,integer-replacement,Integer Replacement,Medium,Dynamic Programming;Greedy;Bit Manipulation;Memoization,Dynamic Programming399398,random-pick-index,Random Pick Index,Medium,Hash Table;Math;Reservoir Sampling;Randomized,Hash Table400399,evaluate-division,Evaluate Division,Medium,Array;String;Depth-First Search;Breadth-First Search;Union-Find;Graph Theory;Shortest Path,Array401400,nth-digit,Nth Digit,Medium,Math;Binary Search,Math402401,binary-watch,Binary Watch,Easy,Backtracking;Bit Manipulation,Backtracking403402,remove-k-digits,Remove K Digits,Medium,String;Stack;Greedy;Monotonic Stack,String404403,frog-jump,Frog Jump,Hard,Array;Dynamic Programming,Array405404,sum-of-left-leaves,Sum of Left Leaves,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree406405,convert-a-number-to-hexadecimal,Convert a Number to Hexadecimal,Easy,Math;String;Bit Manipulation,Math407406,queue-reconstruction-by-height,Queue Reconstruction by Height,Medium,Array;Binary Indexed Tree;Segment Tree;Sorting,Array408407,trapping-rain-water-ii,Trapping Rain Water II,Hard,Array;Breadth-First Search;Heap (Priority Queue);Matrix,Array409408,valid-word-abbreviation,Valid Word Abbreviation,Easy,Two Pointers;String,Two Pointers410409,longest-palindrome,Longest Palindrome,Easy,Hash Table;String;Greedy,Hash Table411410,split-array-largest-sum,Split Array Largest Sum,Hard,Array;Binary Search;Dynamic Programming;Greedy;Prefix Sum,Array412411,minimum-unique-word-abbreviation,Minimum Unique Word Abbreviation,Hard,Array;String;Backtracking;Bit Manipulation,Array413412,fizz-buzz,Fizz Buzz,Easy,Math;String;Simulation,Math414413,arithmetic-slices,Arithmetic Slices,Medium,Array;Dynamic Programming;Sliding Window,Array415414,third-maximum-number,Third Maximum Number,Easy,Array;Sorting,Array416415,add-strings,Add Strings,Easy,Math;String;Simulation,Math417416,partition-equal-subset-sum,Partition Equal Subset Sum,Medium,Array;Dynamic Programming,Array418417,pacific-atlantic-water-flow,Pacific Atlantic Water Flow,Medium,Array;Depth-First Search;Breadth-First Search;Matrix,Array419418,sentence-screen-fitting,Sentence Screen Fitting,Medium,Array;String;Dynamic Programming,Array420419,battleships-in-a-board,Battleships in a Board,Medium,Array;Depth-First Search;Matrix,Array421420,strong-password-checker,Strong Password Checker,Hard,String;Greedy;Heap (Priority Queue),String422421,maximum-xor-of-two-numbers-in-an-array,Maximum XOR of Two Numbers in an Array,Medium,Array;Hash Table;Bit Manipulation;Trie,Array423422,valid-word-square,Valid Word Square,Easy,Array;Matrix,Array424423,reconstruct-original-digits-from-english,Reconstruct Original Digits from English,Medium,Hash Table;Math;String,Hash Table425424,longest-repeating-character-replacement,Longest Repeating Character Replacement,Medium,Hash Table;String;Sliding Window,Hash Table426425,word-squares,Word Squares,Hard,Array;String;Backtracking;Trie,Array427426,convert-binary-search-tree-to-sorted-doubly-linked-list,Convert Binary Search Tree to Sorted Doubly Linked List,Medium,Linked List;Stack;Tree;Depth-First Search;Binary Search Tree;Binary Tree;Doubly-Linked List,Linked List428427,construct-quad-tree,Construct Quad Tree,Medium,Array;Divide and Conquer;Tree;Matrix,Array429428,serialize-and-deserialize-n-ary-tree,Serialize and Deserialize N-ary Tree,Hard,String;Tree;Depth-First Search;Breadth-First Search,String430429,n-ary-tree-level-order-traversal,N-ary Tree Level Order Traversal,Medium,Tree;Breadth-First Search,Tree431430,flatten-a-multilevel-doubly-linked-list,Flatten a Multilevel Doubly Linked List,Medium,Linked List;Depth-First Search;Doubly-Linked List,Linked List432431,encode-n-ary-tree-to-binary-tree,Encode N-ary Tree to Binary Tree,Hard,Tree;Depth-First Search;Breadth-First Search;Design;Binary Tree,Tree433432,all-oone-data-structure,All O`one Data Structure,Hard,Hash Table;Linked List;Design;Doubly-Linked List,Hash Table434433,minimum-genetic-mutation,Minimum Genetic Mutation,Medium,Hash Table;String;Breadth-First Search,Hash Table435434,number-of-segments-in-a-string,Number of Segments in a String,Easy,String,String436435,non-overlapping-intervals,Non-overlapping Intervals,Medium,Array;Dynamic Programming;Greedy;Sorting,Array437436,find-right-interval,Find Right Interval,Medium,Array;Binary Search;Sorting,Array438437,path-sum-iii,Path Sum III,Medium,Tree;Depth-First Search;Binary Tree,Tree439438,find-all-anagrams-in-a-string,Find All Anagrams in a String,Medium,Hash Table;String;Sliding Window,Hash Table440439,ternary-expression-parser,Ternary Expression Parser,Medium,String;Stack;Recursion,String441440,k-th-smallest-in-lexicographical-order,K-th Smallest in Lexicographical Order,Hard,Trie,Trie442441,arranging-coins,Arranging Coins,Easy,Math;Binary Search,Math443442,find-all-duplicates-in-an-array,Find All Duplicates in an Array,Medium,Array;Hash Table;Sorting,Array444443,string-compression,String Compression,Medium,Two Pointers;String,Two Pointers445444,sequence-reconstruction,Sequence Reconstruction,Medium,Array;Graph Theory;Topological Sort,Array446445,add-two-numbers-ii,Add Two Numbers II,Medium,Linked List;Math;Stack,Linked List447446,arithmetic-slices-ii-subsequence,Arithmetic Slices II - Subsequence,Hard,Array;Dynamic Programming,Array448447,number-of-boomerangs,Number of Boomerangs,Medium,Array;Hash Table;Math,Array449448,find-all-numbers-disappeared-in-an-array,Find All Numbers Disappeared in an Array,Easy,Array;Hash Table,Array450449,serialize-and-deserialize-bst,Serialize and Deserialize BST,Medium,String;Tree;Depth-First Search;Breadth-First Search;Design;Binary Search Tree;Binary Tree,String451450,delete-node-in-a-bst,Delete Node in a BST,Medium,Tree;Binary Search Tree;Binary Tree,Tree452451,sort-characters-by-frequency,Sort Characters By Frequency,Medium,Hash Table;String;Sorting;Heap (Priority Queue);Bucket Sort;Counting,Hash Table453452,minimum-number-of-arrows-to-burst-balloons,Minimum Number of Arrows to Burst Balloons,Medium,Array;Greedy;Sorting,Array454453,minimum-moves-to-equal-array-elements,Minimum Moves to Equal Array Elements,Medium,Array;Math,Array455454,4sum-ii,4Sum II,Medium,Array;Hash Table,Array456455,assign-cookies,Assign Cookies,Easy,Array;Two Pointers;Greedy;Sorting,Array457456,132-pattern,132 Pattern,Medium,Array;Binary Search;Stack;Monotonic Stack;Ordered Set,Array458457,circular-array-loop,Circular Array Loop,Medium,Array;Hash Table;Two Pointers,Array459458,poor-pigs,Poor Pigs,Hard,Math;Dynamic Programming;Combinatorics,Math460459,repeated-substring-pattern,Repeated Substring Pattern,Easy,String;String Matching,String461460,lfu-cache,LFU Cache,Hard,Hash Table;Linked List;Design;Doubly-Linked List,Hash Table462461,hamming-distance,Hamming Distance,Easy,Bit Manipulation,Bit Manipulation463462,minimum-moves-to-equal-array-elements-ii,Minimum Moves to Equal Array Elements II,Medium,Array;Math;Sorting,Array464463,island-perimeter,Island Perimeter,Easy,Array;Depth-First Search;Breadth-First Search;Matrix,Array465464,can-i-win,Can I Win,Medium,Math;Dynamic Programming;Bit Manipulation;Memoization;Game Theory;Bitmask,Math466465,optimal-account-balancing,Optimal Account Balancing,Hard,Array;Dynamic Programming;Backtracking;Bit Manipulation;Bitmask,Array467466,count-the-repetitions,Count The Repetitions,Hard,Two Pointers;String;Dynamic Programming,Two Pointers468467,unique-substrings-in-wraparound-string,Unique Substrings in Wraparound String,Medium,String;Dynamic Programming,String469468,validate-ip-address,Validate IP Address,Medium,String,String470469,convex-polygon,Convex Polygon,Medium,Array;Math;Geometry,Array471470,implement-rand10-using-rand7,Implement Rand10() Using Rand7(),Medium,Math;Rejection Sampling;Randomized;Probability and Statistics,Math472471,encode-string-with-shortest-length,Encode String with Shortest Length,Hard,String;Dynamic Programming,String473472,concatenated-words,Concatenated Words,Hard,Array;String;Dynamic Programming;Depth-First Search;Trie;Sorting,Array474473,matchsticks-to-square,Matchsticks to Square,Medium,Array;Dynamic Programming;Backtracking;Bit Manipulation;Bitmask,Array475474,ones-and-zeroes,Ones and Zeroes,Medium,Array;String;Dynamic Programming,Array476475,heaters,Heaters,Medium,Array;Two Pointers;Binary Search;Sorting,Array477476,number-complement,Number Complement,Easy,Bit Manipulation,Bit Manipulation478477,total-hamming-distance,Total Hamming Distance,Medium,Array;Math;Bit Manipulation,Array479478,generate-random-point-in-a-circle,Generate Random Point in a Circle,Medium,Math;Geometry;Rejection Sampling;Randomized,Math480479,largest-palindrome-product,Largest Palindrome Product,Hard,Math;Enumeration,Math481480,sliding-window-median,Sliding Window Median,Hard,Array;Hash Table;Sliding Window;Heap (Priority Queue),Array482481,magical-string,Magical String,Medium,Two Pointers;String,Two Pointers483482,license-key-formatting,License Key Formatting,Easy,String,String484483,smallest-good-base,Smallest Good Base,Hard,Math;Binary Search,Math485484,find-permutation,Find Permutation,Medium,Array;String;Stack;Greedy,Array486485,max-consecutive-ones,Max Consecutive Ones,Easy,Array,Array487486,predict-the-winner,Predict the Winner,Medium,Array;Math;Dynamic Programming;Recursion;Game Theory,Array488487,max-consecutive-ones-ii,Max Consecutive Ones II,Medium,Array;Dynamic Programming;Sliding Window,Array489488,zuma-game,Zuma Game,Hard,String;Dynamic Programming;Stack;Breadth-First Search;Memoization,String490489,robot-room-cleaner,Robot Room Cleaner,Hard,Backtracking;Interactive,Backtracking491490,the-maze,The Maze,Medium,Array;Depth-First Search;Breadth-First Search;Matrix,Array492491,non-decreasing-subsequences,Non-decreasing Subsequences,Medium,Array;Hash Table;Backtracking;Bit Manipulation,Array493492,construct-the-rectangle,Construct the Rectangle,Easy,Math,Math494493,reverse-pairs,Reverse Pairs,Hard,Array;Binary Search;Divide and Conquer;Binary Indexed Tree;Segment Tree;Merge Sort;Ordered Set,Array495494,target-sum,Target Sum,Medium,Array;Dynamic Programming;Backtracking,Array496495,teemo-attacking,Teemo Attacking,Easy,Array;Simulation,Array497496,next-greater-element-i,Next Greater Element I,Easy,Array;Hash Table;Stack;Monotonic Stack,Array498497,random-point-in-non-overlapping-rectangles,Random Point in Non-overlapping Rectangles,Medium,Array;Math;Binary Search;Reservoir Sampling;Prefix Sum;Ordered Set;Randomized,Array499498,diagonal-traverse,Diagonal Traverse,Medium,Array;Matrix;Simulation,Array500499,the-maze-iii,The Maze III,Hard,Array;String;Depth-First Search;Breadth-First Search;Graph Theory;Heap (Priority Queue);Matrix;Shortest Path,Array501500,keyboard-row,Keyboard Row,Easy,Array;Hash Table;String,Array502501,find-mode-in-binary-search-tree,Find Mode in Binary Search Tree,Easy,Tree;Depth-First Search;Binary Search Tree;Binary Tree,Tree503502,ipo,IPO,Hard,Array;Greedy;Sorting;Heap (Priority Queue),Array504503,next-greater-element-ii,Next Greater Element II,Medium,Array;Stack;Monotonic Stack,Array505504,base-7,Base 7,Easy,Math;String,Math506505,the-maze-ii,The Maze II,Medium,Array;Depth-First Search;Breadth-First Search;Graph Theory;Heap (Priority Queue);Matrix;Shortest Path,Array507506,relative-ranks,Relative Ranks,Easy,Array;Sorting;Heap (Priority Queue),Array508507,perfect-number,Perfect Number,Easy,Math,Math509508,most-frequent-subtree-sum,Most Frequent Subtree Sum,Medium,Hash Table;Tree;Depth-First Search;Binary Tree,Hash Table510509,fibonacci-number,Fibonacci Number,Easy,Math;Dynamic Programming;Recursion;Memoization,Math511510,inorder-successor-in-bst-ii,Inorder Successor in BST II,Medium,Tree;Binary Search Tree;Binary Tree,Tree512511,game-play-analysis-i,Game Play Analysis I,Easy,Database,Database513512,game-play-analysis-ii,Game Play Analysis II,Easy,Database,Database514513,find-bottom-left-tree-value,Find Bottom Left Tree Value,Medium,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree515514,freedom-trail,Freedom Trail,Hard,String;Dynamic Programming;Depth-First Search;Breadth-First Search,String516515,find-largest-value-in-each-tree-row,Find Largest Value in Each Tree Row,Medium,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree517516,longest-palindromic-subsequence,Longest Palindromic Subsequence,Medium,String;Dynamic Programming,String518517,super-washing-machines,Super Washing Machines,Hard,Array;Greedy,Array519518,coin-change-ii,Coin Change II,Medium,Array;Dynamic Programming,Array520519,random-flip-matrix,Random Flip Matrix,Medium,Hash Table;Math;Reservoir Sampling;Randomized,Hash Table521520,detect-capital,Detect Capital,Easy,String,String522521,longest-uncommon-subsequence-i,Longest Uncommon Subsequence I,Easy,String,String523522,longest-uncommon-subsequence-ii,Longest Uncommon Subsequence II,Medium,Array;Hash Table;Two Pointers;String;Sorting,Array524523,continuous-subarray-sum,Continuous Subarray Sum,Medium,Array;Hash Table;Math;Prefix Sum,Array525524,longest-word-in-dictionary-through-deleting,Longest Word in Dictionary through Deleting,Medium,Array;Two Pointers;String;Sorting,Array526525,contiguous-array,Contiguous Array,Medium,Array;Hash Table;Prefix Sum,Array527526,beautiful-arrangement,Beautiful Arrangement,Medium,Array;Dynamic Programming;Backtracking;Bit Manipulation;Bitmask,Array528527,word-abbreviation,Word Abbreviation,Hard,Array;String;Greedy;Trie;Sorting,Array529528,random-pick-with-weight,Random Pick with Weight,Medium,Array;Math;Binary Search;Prefix Sum;Randomized,Array530529,minesweeper,Minesweeper,Medium,Array;Depth-First Search;Breadth-First Search;Matrix,Array531530,minimum-absolute-difference-in-bst,Minimum Absolute Difference in BST,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Search Tree;Binary Tree,Tree532531,lonely-pixel-i,Lonely Pixel I,Medium,Array;Hash Table;Matrix,Array533532,k-diff-pairs-in-an-array,K-diff Pairs in an Array,Medium,Array;Hash Table;Two Pointers;Binary Search;Sorting,Array534533,lonely-pixel-ii,Lonely Pixel II,Medium,Array;Hash Table;Matrix,Array535534,game-play-analysis-iii,Game Play Analysis III,Medium,Database,Database536535,encode-and-decode-tinyurl,Encode and Decode TinyURL,Medium,Hash Table;String;Design;Hash Function,Hash Table537536,construct-binary-tree-from-string,Construct Binary Tree from String,Medium,String;Stack;Tree;Depth-First Search;Binary Tree,String538537,complex-number-multiplication,Complex Number Multiplication,Medium,Math;String;Simulation,Math539538,convert-bst-to-greater-tree,Convert BST to Greater Tree,Medium,Tree;Depth-First Search;Binary Search Tree;Binary Tree,Tree540539,minimum-time-difference,Minimum Time Difference,Medium,Array;Math;String;Sorting,Array541540,single-element-in-a-sorted-array,Single Element in a Sorted Array,Medium,Array;Binary Search,Array542541,reverse-string-ii,Reverse String II,Easy,Two Pointers;String,Two Pointers543542,01-matrix,01 Matrix,Medium,Array;Dynamic Programming;Breadth-First Search;Matrix,Array544543,diameter-of-binary-tree,Diameter of Binary Tree,Easy,Tree;Depth-First Search;Binary Tree,Tree545544,output-contest-matches,Output Contest Matches,Medium,String;Recursion;Simulation,String546545,boundary-of-binary-tree,Boundary of Binary Tree,Medium,Tree;Depth-First Search;Binary Tree,Tree547546,remove-boxes,Remove Boxes,Hard,Array;Dynamic Programming;Memoization,Array548547,number-of-provinces,Number of Provinces,Medium,Depth-First Search;Breadth-First Search;Union-Find;Graph Theory,Depth-First Search549548,split-array-with-equal-sum,Split Array with Equal Sum,Hard,Array;Hash Table;Prefix Sum,Array550549,binary-tree-longest-consecutive-sequence-ii,Binary Tree Longest Consecutive Sequence II,Medium,Tree;Depth-First Search;Binary Tree,Tree551550,game-play-analysis-iv,Game Play Analysis IV,Medium,Database,Database552551,student-attendance-record-i,Student Attendance Record I,Easy,String,String553552,student-attendance-record-ii,Student Attendance Record II,Hard,Dynamic Programming,Dynamic Programming554553,optimal-division,Optimal Division,Medium,Array;Math;Dynamic Programming,Array555554,brick-wall,Brick Wall,Medium,Array;Hash Table,Array556555,split-concatenated-strings,Split Concatenated Strings,Medium,Array;String;Greedy,Array557556,next-greater-element-iii,Next Greater Element III,Medium,Math;Two Pointers;String,Math558557,reverse-words-in-a-string-iii,Reverse Words in a String III,Easy,Two Pointers;String,Two Pointers559558,logical-or-of-two-binary-grids-represented-as-quad-trees,Logical OR of Two Binary Grids Represented as Quad-Trees,Medium,Divide and Conquer;Tree,Divide and Conquer560559,maximum-depth-of-n-ary-tree,Maximum Depth of N-ary Tree,Easy,Tree;Depth-First Search;Breadth-First Search,Tree561560,subarray-sum-equals-k,Subarray Sum Equals K,Medium,Array;Hash Table;Prefix Sum,Array562561,array-partition,Array Partition,Easy,Array;Greedy;Sorting;Counting Sort,Array563562,longest-line-of-consecutive-one-in-matrix,Longest Line of Consecutive One in Matrix,Medium,Array;Dynamic Programming;Matrix,Array564563,binary-tree-tilt,Binary Tree Tilt,Easy,Tree;Depth-First Search;Binary Tree,Tree565564,find-the-closest-palindrome,Find the Closest Palindrome,Hard,Math;String,Math566565,array-nesting,Array Nesting,Medium,Array;Depth-First Search,Array567566,reshape-the-matrix,Reshape the Matrix,Easy,Array;Matrix;Simulation,Array568567,permutation-in-string,Permutation in String,Medium,Hash Table;Two Pointers;String;Sliding Window,Hash Table569568,maximum-vacation-days,Maximum Vacation Days,Hard,Array;Dynamic Programming;Matrix,Array570569,median-employee-salary,Median Employee Salary,Hard,Database,Database571570,managers-with-at-least-5-direct-reports,Managers with at Least 5 Direct Reports,Medium,Database,Database572571,find-median-given-frequency-of-numbers,Find Median Given Frequency of Numbers,Hard,Database,Database573572,subtree-of-another-tree,Subtree of Another Tree,Easy,Tree;Depth-First Search;String Matching;Binary Tree;Hash Function,Tree574573,squirrel-simulation,Squirrel Simulation,Medium,Array;Math,Array575574,winning-candidate,Winning Candidate,Medium,Database,Database576575,distribute-candies,Distribute Candies,Easy,Array;Hash Table,Array577576,out-of-boundary-paths,Out of Boundary Paths,Medium,Dynamic Programming,Dynamic Programming578577,employee-bonus,Employee Bonus,Easy,Database,Database579578,get-highest-answer-rate-question,Get Highest Answer Rate Question,Medium,Database,Database580579,find-cumulative-salary-of-an-employee,Find Cumulative Salary of an Employee,Hard,Database,Database581580,count-student-number-in-departments,Count Student Number in Departments,Medium,Database,Database582581,shortest-unsorted-continuous-subarray,Shortest Unsorted Continuous Subarray,Medium,Array;Two Pointers;Stack;Greedy;Sorting;Monotonic Stack,Array583582,kill-process,Kill Process,Medium,Array;Hash Table;Tree;Depth-First Search;Breadth-First Search,Array584583,delete-operation-for-two-strings,Delete Operation for Two Strings,Medium,String;Dynamic Programming,String585584,find-customer-referee,Find Customer Referee,Easy,Database,Database586585,investments-in-2016,Investments in 2016,Medium,Database,Database587586,customer-placing-the-largest-number-of-orders,Customer Placing the Largest Number of Orders,Easy,Database,Database588587,erect-the-fence,Erect the Fence,Hard,Array;Math;Geometry,Array589588,design-in-memory-file-system,Design In-Memory File System,Hard,Hash Table;String;Design;Trie;Sorting,Hash Table590589,n-ary-tree-preorder-traversal,N-ary Tree Preorder Traversal,Easy,Stack;Tree;Depth-First Search,Stack591590,n-ary-tree-postorder-traversal,N-ary Tree Postorder Traversal,Easy,Stack;Tree;Depth-First Search,Stack592591,tag-validator,Tag Validator,Hard,String;Stack,String593592,fraction-addition-and-subtraction,Fraction Addition and Subtraction,Medium,Math;String;Simulation,Math594593,valid-square,Valid Square,Medium,Math;Geometry,Math595594,longest-harmonious-subsequence,Longest Harmonious Subsequence,Easy,Array;Hash Table;Sliding Window;Sorting;Counting,Array596595,big-countries,Big Countries,Easy,Database,Database597596,classes-with-at-least-5-students,Classes With at Least 5 Students,Easy,Database,Database598597,friend-requests-i-overall-acceptance-rate,Friend Requests I: Overall Acceptance Rate,Easy,Database,Database599598,range-addition-ii,Range Addition II,Easy,Array;Math,Array600599,minimum-index-sum-of-two-lists,Minimum Index Sum of Two Lists,Easy,Array;Hash Table;String,Array601600,non-negative-integers-without-consecutive-ones,Non-negative Integers without Consecutive Ones,Hard,Dynamic Programming,Dynamic Programming602601,human-traffic-of-stadium,Human Traffic of Stadium,Hard,Database,Database603602,friend-requests-ii-who-has-the-most-friends,Friend Requests II: Who Has the Most Friends,Medium,Database,Database604603,consecutive-available-seats,Consecutive Available Seats,Easy,Database,Database605604,design-compressed-string-iterator,Design Compressed String Iterator,Easy,Array;String;Design;Iterator,Array606605,can-place-flowers,Can Place Flowers,Easy,Array;Greedy,Array607606,construct-string-from-binary-tree,Construct String from Binary Tree,Medium,String;Tree;Depth-First Search;Binary Tree,String608607,sales-person,Sales Person,Easy,Database,Database609608,tree-node,Tree Node,Medium,Database,Database610609,find-duplicate-file-in-system,Find Duplicate File in System,Medium,Array;Hash Table;String,Array611610,triangle-judgement,Triangle Judgement,Easy,Database,Database612611,valid-triangle-number,Valid Triangle Number,Medium,Array;Two Pointers;Binary Search;Greedy;Sorting,Array613612,shortest-distance-in-a-plane,Shortest Distance in a Plane,Medium,Database,Database614613,shortest-distance-in-a-line,Shortest Distance in a Line,Easy,Database,Database615614,second-degree-follower,Second Degree Follower,Medium,Database,Database616615,average-salary-departments-vs-company,Average Salary: Departments VS Company,Hard,Database,Database617616,add-bold-tag-in-string,Add Bold Tag in String,Medium,Array;Hash Table;String;Trie;String Matching,Array618617,merge-two-binary-trees,Merge Two Binary Trees,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree619618,students-report-by-geography,Students Report By Geography,Hard,Database,Database620619,biggest-single-number,Biggest Single Number,Easy,Database,Database621620,not-boring-movies,Not Boring Movies,Easy,Database,Database622621,task-scheduler,Task Scheduler,Medium,Array;Hash Table;Greedy;Sorting;Heap (Priority Queue);Counting,Array623622,design-circular-queue,Design Circular Queue,Medium,Array;Linked List;Design;Queue,Array624623,add-one-row-to-tree,Add One Row to Tree,Medium,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree625624,maximum-distance-in-arrays,Maximum Distance in Arrays,Medium,Array;Greedy,Array626625,minimum-factorization,Minimum Factorization,Medium,Math;Greedy,Math627626,exchange-seats,Exchange Seats,Medium,Database,Database628627,swap-sex-of-employees,Swap Sex of Employees,Easy,Database,Database629628,maximum-product-of-three-numbers,Maximum Product of Three Numbers,Easy,Array;Math;Sorting,Array630629,k-inverse-pairs-array,K Inverse Pairs Array,Hard,Dynamic Programming,Dynamic Programming631630,course-schedule-iii,Course Schedule III,Hard,Array;Greedy;Sorting;Heap (Priority Queue),Array632631,design-excel-sum-formula,Design Excel Sum Formula,Hard,Array;Hash Table;String;Graph Theory;Design;Topological Sort;Matrix,Array633632,smallest-range-covering-elements-from-k-lists,Smallest Range Covering Elements from K Lists,Hard,Array;Hash Table;Greedy;Sliding Window;Sorting;Heap (Priority Queue),Array634633,sum-of-square-numbers,Sum of Square Numbers,Medium,Math;Two Pointers;Binary Search,Math635634,find-the-derangement-of-an-array,Find the Derangement of An Array,Medium,Math;Dynamic Programming;Combinatorics,Math636635,design-log-storage-system,Design Log Storage System,Medium,Hash Table;String;Design;Ordered Set,Hash Table637636,exclusive-time-of-functions,Exclusive Time of Functions,Medium,Array;Stack,Array638637,average-of-levels-in-binary-tree,Average of Levels in Binary Tree,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree639638,shopping-offers,Shopping Offers,Medium,Array;Dynamic Programming;Backtracking;Bit Manipulation;Memoization;Bitmask,Array640639,decode-ways-ii,Decode Ways II,Hard,String;Dynamic Programming,String641640,solve-the-equation,Solve the Equation,Medium,Math;String;Simulation,Math642641,design-circular-deque,Design Circular Deque,Medium,Array;Linked List;Design;Queue,Array643642,design-search-autocomplete-system,Design Search Autocomplete System,Hard,String;Depth-First Search;Design;Trie;Sorting;Heap (Priority Queue);Data Stream,String644643,maximum-average-subarray-i,Maximum Average Subarray I,Easy,Array;Sliding Window,Array645644,maximum-average-subarray-ii,Maximum Average Subarray II,Hard,Array;Binary Search;Prefix Sum,Array646645,set-mismatch,Set Mismatch,Easy,Array;Hash Table;Bit Manipulation;Sorting,Array647646,maximum-length-of-pair-chain,Maximum Length of Pair Chain,Medium,Array;Dynamic Programming;Greedy;Sorting,Array648647,palindromic-substrings,Palindromic Substrings,Medium,Two Pointers;String;Dynamic Programming,Two Pointers649648,replace-words,Replace Words,Medium,Array;Hash Table;String;Trie,Array650649,dota2-senate,Dota2 Senate,Medium,String;Greedy;Queue,String651650,2-keys-keyboard,2 Keys Keyboard,Medium,Math;Dynamic Programming,Math652651,4-keys-keyboard,4 Keys Keyboard,Medium,Math;Dynamic Programming,Math653652,find-duplicate-subtrees,Find Duplicate Subtrees,Medium,Hash Table;Tree;Depth-First Search;Binary Tree,Hash Table654653,two-sum-iv-input-is-a-bst,Two Sum IV - Input is a BST,Easy,Hash Table;Two Pointers;Tree;Depth-First Search;Breadth-First Search;Binary Search Tree;Binary Tree,Hash Table655654,maximum-binary-tree,Maximum Binary Tree,Medium,Array;Divide and Conquer;Stack;Tree;Monotonic Stack;Binary Tree,Array656655,print-binary-tree,Print Binary Tree,Medium,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree657656,coin-path,Coin Path,Hard,Array;Dynamic Programming,Array658657,robot-return-to-origin,Robot Return to Origin,Easy,String;Simulation,String659658,find-k-closest-elements,Find K Closest Elements,Medium,Array;Two Pointers;Binary Search;Sliding Window;Sorting;Heap (Priority Queue),Array660659,split-array-into-consecutive-subsequences,Split Array into Consecutive Subsequences,Medium,Array;Hash Table;Greedy;Heap (Priority Queue),Array661660,remove-9,Remove 9,Hard,Math,Math662661,image-smoother,Image Smoother,Easy,Array;Matrix,Array663662,maximum-width-of-binary-tree,Maximum Width of Binary Tree,Medium,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree664663,equal-tree-partition,Equal Tree Partition,Medium,Tree;Depth-First Search;Binary Tree,Tree665664,strange-printer,Strange Printer,Hard,String;Dynamic Programming,String666665,non-decreasing-array,Non-decreasing Array,Medium,Array,Array667666,path-sum-iv,Path Sum IV,Medium,Array;Hash Table;Tree;Depth-First Search;Binary Tree,Array668667,beautiful-arrangement-ii,Beautiful Arrangement II,Medium,Array;Math,Array669668,kth-smallest-number-in-multiplication-table,Kth Smallest Number in Multiplication Table,Hard,Math;Binary Search,Math670669,trim-a-binary-search-tree,Trim a Binary Search Tree,Medium,Tree;Depth-First Search;Binary Search Tree;Binary Tree,Tree671670,maximum-swap,Maximum Swap,Medium,Math;Greedy,Math672671,second-minimum-node-in-a-binary-tree,Second Minimum Node In a Binary Tree,Easy,Tree;Depth-First Search;Binary Tree,Tree673672,bulb-switcher-ii,Bulb Switcher II,Medium,Math;Bit Manipulation;Depth-First Search;Breadth-First Search,Math674673,number-of-longest-increasing-subsequence,Number of Longest Increasing Subsequence,Medium,Array;Dynamic Programming;Binary Indexed Tree;Segment Tree,Array675674,longest-continuous-increasing-subsequence,Longest Continuous Increasing Subsequence,Easy,Array,Array676675,cut-off-trees-for-golf-event,Cut Off Trees for Golf Event,Hard,Array;Breadth-First Search;Heap (Priority Queue);Matrix,Array677676,implement-magic-dictionary,Implement Magic Dictionary,Medium,Hash Table;String;Depth-First Search;Design;Trie,Hash Table678677,map-sum-pairs,Map Sum Pairs,Medium,Hash Table;String;Design;Trie,Hash Table679678,valid-parenthesis-string,Valid Parenthesis String,Medium,String;Dynamic Programming;Stack;Greedy,String680679,24-game,24 Game,Hard,Array;Math;Backtracking,Array681680,valid-palindrome-ii,Valid Palindrome II,Easy,Two Pointers;String;Greedy,Two Pointers682681,next-closest-time,Next Closest Time,Medium,Hash Table;String;Backtracking;Enumeration,Hash Table683682,baseball-game,Baseball Game,Easy,Array;Stack;Simulation,Array684683,k-empty-slots,K Empty Slots,Hard,Array;Binary Indexed Tree;Segment Tree;Queue;Sliding Window;Heap (Priority Queue);Ordered Set;Monotonic Queue,Array685684,redundant-connection,Redundant Connection,Medium,Depth-First Search;Breadth-First Search;Union-Find;Graph Theory,Depth-First Search686685,redundant-connection-ii,Redundant Connection II,Hard,Depth-First Search;Breadth-First Search;Union-Find;Graph Theory,Depth-First Search687686,repeated-string-match,Repeated String Match,Medium,String;String Matching,String688687,longest-univalue-path,Longest Univalue Path,Medium,Tree;Depth-First Search;Binary Tree,Tree689688,knight-probability-in-chessboard,Knight Probability in Chessboard,Medium,Dynamic Programming,Dynamic Programming690689,maximum-sum-of-3-non-overlapping-subarrays,Maximum Sum of 3 Non-Overlapping Subarrays,Hard,Array;Dynamic Programming;Sliding Window;Prefix Sum,Array691690,employee-importance,Employee Importance,Medium,Array;Hash Table;Tree;Depth-First Search;Breadth-First Search,Array692691,stickers-to-spell-word,Stickers to Spell Word,Hard,Array;Hash Table;String;Dynamic Programming;Backtracking;Bit Manipulation;Memoization;Bitmask,Array693692,top-k-frequent-words,Top K Frequent Words,Medium,Array;Hash Table;String;Trie;Sorting;Heap (Priority Queue);Bucket Sort;Counting,Array694693,binary-number-with-alternating-bits,Binary Number with Alternating Bits,Easy,Bit Manipulation,Bit Manipulation695694,number-of-distinct-islands,Number of Distinct Islands,Medium,Array;Hash Table;Depth-First Search;Breadth-First Search;Union-Find;Sorting;Matrix;Hash Function,Array696695,max-area-of-island,Max Area of Island,Medium,Array;Depth-First Search;Breadth-First Search;Union-Find;Matrix,Array697696,count-binary-substrings,Count Binary Substrings,Easy,Two Pointers;String,Two Pointers698697,degree-of-an-array,Degree of an Array,Easy,Array;Hash Table,Array699698,partition-to-k-equal-sum-subsets,Partition to K Equal Sum Subsets,Medium,Array;Dynamic Programming;Backtracking;Bit Manipulation;Memoization;Bitmask,Array700699,falling-squares,Falling Squares,Hard,Array;Segment Tree;Ordered Set,Array701700,search-in-a-binary-search-tree,Search in a Binary Search Tree,Easy,Tree;Binary Search Tree;Binary Tree,Tree702701,insert-into-a-binary-search-tree,Insert into a Binary Search Tree,Medium,Tree;Binary Search Tree;Binary Tree,Tree703702,search-in-a-sorted-array-of-unknown-size,Search in a Sorted Array of Unknown Size,Medium,Array;Binary Search;Interactive,Array704703,kth-largest-element-in-a-stream,Kth Largest Element in a Stream,Easy,Tree;Design;Binary Search Tree;Heap (Priority Queue);Binary Tree;Data Stream,Tree705704,binary-search,Binary Search,Easy,Array;Binary Search,Array706705,design-hashset,Design HashSet,Easy,Array;Hash Table;Linked List;Design;Hash Function,Array707706,design-hashmap,Design HashMap,Easy,Array;Hash Table;Linked List;Design;Hash Function,Array708707,design-linked-list,Design Linked List,Medium,Linked List;Design,Linked List709708,insert-into-a-sorted-circular-linked-list,Insert into a Sorted Circular Linked List,Medium,Linked List,Linked List710709,to-lower-case,To Lower Case,Easy,String,String711710,random-pick-with-blacklist,Random Pick with Blacklist,Hard,Array;Hash Table;Math;Binary Search;Sorting;Randomized,Array712711,number-of-distinct-islands-ii,Number of Distinct Islands II,Hard,Array;Hash Table;Depth-First Search;Breadth-First Search;Union-Find;Sorting;Matrix;Hash Function,Array713712,minimum-ascii-delete-sum-for-two-strings,Minimum ASCII Delete Sum for Two Strings,Medium,String;Dynamic Programming,String714713,subarray-product-less-than-k,Subarray Product Less Than K,Medium,Array;Binary Search;Sliding Window;Prefix Sum,Array715714,best-time-to-buy-and-sell-stock-with-transaction-fee,Best Time to Buy and Sell Stock with Transaction Fee,Medium,Array;Dynamic Programming;Greedy,Array716715,range-module,Range Module,Hard,Design;Segment Tree;Ordered Set,Design717716,max-stack,Max Stack,Hard,Linked List;Stack;Design;Doubly-Linked List;Ordered Set,Linked List718717,1-bit-and-2-bit-characters,1-bit and 2-bit Characters,Easy,Array,Array719718,maximum-length-of-repeated-subarray,Maximum Length of Repeated Subarray,Medium,Array;Binary Search;Dynamic Programming;Sliding Window;Rolling Hash;Hash Function,Array720719,find-k-th-smallest-pair-distance,Find K-th Smallest Pair Distance,Hard,Array;Two Pointers;Binary Search;Sorting,Array721720,longest-word-in-dictionary,Longest Word in Dictionary,Medium,Array;Hash Table;String;Trie;Sorting,Array722721,accounts-merge,Accounts Merge,Medium,Array;Hash Table;String;Depth-First Search;Breadth-First Search;Union-Find;Sorting,Array723722,remove-comments,Remove Comments,Medium,Array;String,Array724723,candy-crush,Candy Crush,Medium,Array;Two Pointers;Matrix;Simulation,Array725724,find-pivot-index,Find Pivot Index,Easy,Array;Prefix Sum,Array726725,split-linked-list-in-parts,Split Linked List in Parts,Medium,Linked List,Linked List727726,number-of-atoms,Number of Atoms,Hard,Hash Table;String;Stack;Sorting,Hash Table728727,minimum-window-subsequence,Minimum Window Subsequence,Hard,String;Dynamic Programming;Sliding Window,String729728,self-dividing-numbers,Self Dividing Numbers,Easy,Math,Math730729,my-calendar-i,My Calendar I,Medium,Array;Binary Search;Design;Segment Tree;Ordered Set,Array731730,count-different-palindromic-subsequences,Count Different Palindromic Subsequences,Hard,String;Dynamic Programming,String732731,my-calendar-ii,My Calendar II,Medium,Array;Binary Search;Design;Segment Tree;Prefix Sum;Ordered Set,Array733732,my-calendar-iii,My Calendar III,Hard,Binary Search;Design;Segment Tree;Prefix Sum;Ordered Set,Binary Search734733,flood-fill,Flood Fill,Easy,Array;Depth-First Search;Breadth-First Search;Matrix,Array735734,sentence-similarity,Sentence Similarity,Easy,Array;Hash Table;String,Array736735,asteroid-collision,Asteroid Collision,Medium,Array;Stack;Simulation,Array737736,parse-lisp-expression,Parse Lisp Expression,Hard,Hash Table;String;Stack;Recursion,Hash Table738737,sentence-similarity-ii,Sentence Similarity II,Medium,Array;Hash Table;String;Depth-First Search;Breadth-First Search;Union-Find,Array739738,monotone-increasing-digits,Monotone Increasing Digits,Medium,Math;Greedy,Math740739,daily-temperatures,Daily Temperatures,Medium,Array;Stack;Monotonic Stack,Array741740,delete-and-earn,Delete and Earn,Medium,Array;Hash Table;Dynamic Programming,Array742741,cherry-pickup,Cherry Pickup,Hard,Array;Dynamic Programming;Matrix,Array743742,closest-leaf-in-a-binary-tree,Closest Leaf in a Binary Tree,Medium,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree744743,network-delay-time,Network Delay Time,Medium,Depth-First Search;Breadth-First Search;Graph Theory;Heap (Priority Queue);Shortest Path,Depth-First Search745744,find-smallest-letter-greater-than-target,Find Smallest Letter Greater Than Target,Easy,Array;Binary Search,Array746745,prefix-and-suffix-search,Prefix and Suffix Search,Hard,Array;Hash Table;String;Design;Trie,Array747746,min-cost-climbing-stairs,Min Cost Climbing Stairs,Easy,Array;Dynamic Programming,Array748747,largest-number-at-least-twice-of-others,Largest Number At Least Twice of Others,Easy,Array;Sorting,Array749748,shortest-completing-word,Shortest Completing Word,Easy,Array;Hash Table;String,Array750749,contain-virus,Contain Virus,Hard,Array;Depth-First Search;Breadth-First Search;Matrix;Simulation,Array751750,number-of-corner-rectangles,Number Of Corner Rectangles,Medium,Array;Math;Dynamic Programming;Matrix,Array752751,ip-to-cidr,IP to CIDR,Medium,String;Bit Manipulation,String753752,open-the-lock,Open the Lock,Medium,Array;Hash Table;String;Breadth-First Search,Array754753,cracking-the-safe,Cracking the Safe,Hard,String;Depth-First Search;Graph Theory;Eulerian Circuit,String755754,reach-a-number,Reach a Number,Medium,Math;Binary Search,Math756755,pour-water,Pour Water,Medium,Array;Simulation,Array757756,pyramid-transition-matrix,Pyramid Transition Matrix,Medium,Hash Table;String;Backtracking;Bit Manipulation,Hash Table758757,set-intersection-size-at-least-two,Set Intersection Size At Least Two,Hard,Array;Greedy;Sorting,Array759758,bold-words-in-string,Bold Words in String,Medium,Array;Hash Table;String;Trie;String Matching,Array760759,employee-free-time,Employee Free Time,Hard,Array;Sweep Line;Sorting;Heap (Priority Queue),Array761760,find-anagram-mappings,Find Anagram Mappings,Easy,Array;Hash Table,Array762761,special-binary-string,Special Binary String,Hard,String;Divide and Conquer;Sorting,String763762,prime-number-of-set-bits-in-binary-representation,Prime Number of Set Bits in Binary Representation,Easy,Math;Bit Manipulation,Math764763,partition-labels,Partition Labels,Medium,Hash Table;Two Pointers;String;Greedy,Hash Table765764,largest-plus-sign,Largest Plus Sign,Medium,Array;Dynamic Programming,Array766765,couples-holding-hands,Couples Holding Hands,Hard,Greedy;Depth-First Search;Breadth-First Search;Union-Find;Graph Theory,Greedy767766,toeplitz-matrix,Toeplitz Matrix,Easy,Array;Matrix,Array768767,reorganize-string,Reorganize String,Medium,Hash Table;String;Greedy;Sorting;Heap (Priority Queue);Counting,Hash Table769768,max-chunks-to-make-sorted-ii,Max Chunks To Make Sorted II,Hard,Array;Stack;Greedy;Sorting;Monotonic Stack,Array770769,max-chunks-to-make-sorted,Max Chunks To Make Sorted,Medium,Array;Stack;Greedy;Sorting;Monotonic Stack,Array771770,basic-calculator-iv,Basic Calculator IV,Hard,Hash Table;Math;String;Stack;Recursion,Hash Table772771,jewels-and-stones,Jewels and Stones,Easy,Hash Table;String,Hash Table773772,basic-calculator-iii,Basic Calculator III,Hard,Math;String;Stack;Recursion,Math774773,sliding-puzzle,Sliding Puzzle,Hard,Array;Dynamic Programming;Backtracking;Breadth-First Search;Memoization;Matrix,Array775774,minimize-max-distance-to-gas-station,Minimize Max Distance to Gas Station,Hard,Array;Binary Search,Array776775,global-and-local-inversions,Global and Local Inversions,Medium,Array;Math,Array777776,split-bst,Split BST,Medium,Tree;Binary Search Tree;Recursion;Binary Tree,Tree778777,swap-adjacent-in-lr-string,Swap Adjacent in LR String,Medium,Two Pointers;String,Two Pointers779778,swim-in-rising-water,Swim in Rising Water,Hard,Array;Binary Search;Depth-First Search;Breadth-First Search;Union-Find;Heap (Priority Queue);Matrix,Array780779,k-th-symbol-in-grammar,K-th Symbol in Grammar,Medium,Math;Bit Manipulation;Recursion,Math781780,reaching-points,Reaching Points,Hard,Math,Math782781,rabbits-in-forest,Rabbits in Forest,Medium,Array;Hash Table;Math;Greedy,Array783782,transform-to-chessboard,Transform to Chessboard,Hard,Array;Math;Bit Manipulation;Matrix,Array784783,minimum-distance-between-bst-nodes,Minimum Distance Between BST Nodes,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Search Tree;Binary Tree,Tree785784,letter-case-permutation,Letter Case Permutation,Medium,String;Backtracking;Bit Manipulation,String786785,is-graph-bipartite,Is Graph Bipartite?,Medium,Depth-First Search;Breadth-First Search;Union-Find;Graph Theory,Depth-First Search787786,k-th-smallest-prime-fraction,K-th Smallest Prime Fraction,Medium,Array;Two Pointers;Binary Search;Sorting;Heap (Priority Queue),Array788787,cheapest-flights-within-k-stops,Cheapest Flights Within K Stops,Medium,Dynamic Programming;Depth-First Search;Breadth-First Search;Graph Theory;Heap (Priority Queue);Shortest Path,Dynamic Programming789788,rotated-digits,Rotated Digits,Medium,Math;Dynamic Programming,Math790789,escape-the-ghosts,Escape The Ghosts,Medium,Array;Math,Array791790,domino-and-tromino-tiling,Domino and Tromino Tiling,Medium,Dynamic Programming,Dynamic Programming792791,custom-sort-string,Custom Sort String,Medium,Hash Table;String;Sorting,Hash Table793792,number-of-matching-subsequences,Number of Matching Subsequences,Medium,Array;Hash Table;String;Binary Search;Dynamic Programming;Trie;Sorting,Array794793,preimage-size-of-factorial-zeroes-function,Preimage Size of Factorial Zeroes Function,Hard,Math;Binary Search,Math795794,valid-tic-tac-toe-state,Valid Tic-Tac-Toe State,Medium,Array;Matrix,Array796795,number-of-subarrays-with-bounded-maximum,Number of Subarrays with Bounded Maximum,Medium,Array;Two Pointers,Array797796,rotate-string,Rotate String,Easy,String;String Matching,String798797,all-paths-from-source-to-target,All Paths From Source to Target,Medium,Backtracking;Depth-First Search;Breadth-First Search;Graph Theory,Backtracking799798,smallest-rotation-with-highest-score,Smallest Rotation with Highest Score,Hard,Array;Prefix Sum,Array800799,champagne-tower,Champagne Tower,Medium,Dynamic Programming,Dynamic Programming801800,similar-rgb-color,Similar RGB Color,Easy,Math;String;Enumeration,Math802801,minimum-swaps-to-make-sequences-increasing,Minimum Swaps To Make Sequences Increasing,Hard,Array;Dynamic Programming,Array803802,find-eventual-safe-states,Find Eventual Safe States,Medium,Depth-First Search;Breadth-First Search;Graph Theory;Topological Sort,Depth-First Search804803,bricks-falling-when-hit,Bricks Falling When Hit,Hard,Array;Union-Find;Matrix,Array805804,unique-morse-code-words,Unique Morse Code Words,Easy,Array;Hash Table;String,Array806805,split-array-with-same-average,Split Array With Same Average,Hard,Array;Hash Table;Math;Dynamic Programming;Bit Manipulation;Bitmask,Array807806,number-of-lines-to-write-string,Number of Lines To Write String,Easy,Array;String,Array808807,max-increase-to-keep-city-skyline,Max Increase to Keep City Skyline,Medium,Array;Greedy;Matrix,Array809808,soup-servings,Soup Servings,Medium,Math;Dynamic Programming;Probability and Statistics,Math810809,expressive-words,Expressive Words,Medium,Array;Two Pointers;String,Array811810,chalkboard-xor-game,Chalkboard XOR Game,Hard,Array;Math;Bit Manipulation;Brainteaser;Game Theory,Array812811,subdomain-visit-count,Subdomain Visit Count,Medium,Array;Hash Table;String;Counting,Array813812,largest-triangle-area,Largest Triangle Area,Easy,Array;Math;Geometry,Array814813,largest-sum-of-averages,Largest Sum of Averages,Medium,Array;Dynamic Programming;Prefix Sum,Array815814,binary-tree-pruning,Binary Tree Pruning,Medium,Tree;Depth-First Search;Binary Tree,Tree816815,bus-routes,Bus Routes,Hard,Array;Hash Table;Breadth-First Search,Array817816,ambiguous-coordinates,Ambiguous Coordinates,Medium,String;Backtracking;Enumeration,String818817,linked-list-components,Linked List Components,Medium,Array;Hash Table;Linked List,Array819818,race-car,Race Car,Hard,Dynamic Programming,Dynamic Programming820819,most-common-word,Most Common Word,Easy,Array;Hash Table;String;Counting,Array821820,short-encoding-of-words,Short Encoding of Words,Medium,Array;Hash Table;String;Trie,Array822821,shortest-distance-to-a-character,Shortest Distance to a Character,Easy,Array;Two Pointers;String,Array823822,card-flipping-game,Card Flipping Game,Medium,Array;Hash Table,Array824823,binary-trees-with-factors,Binary Trees With Factors,Medium,Array;Hash Table;Dynamic Programming;Sorting,Array825824,goat-latin,Goat Latin,Easy,String,String826825,friends-of-appropriate-ages,Friends Of Appropriate Ages,Medium,Array;Two Pointers;Binary Search;Sorting,Array827826,most-profit-assigning-work,Most Profit Assigning Work,Medium,Array;Two Pointers;Binary Search;Greedy;Sorting,Array828827,making-a-large-island,Making A Large Island,Hard,Array;Depth-First Search;Breadth-First Search;Union-Find;Matrix,Array829828,count-unique-characters-of-all-substrings-of-a-given-string,Count Unique Characters of All Substrings of a Given String,Hard,Hash Table;String;Dynamic Programming,Hash Table830829,consecutive-numbers-sum,Consecutive Numbers Sum,Hard,Math;Enumeration,Math831830,positions-of-large-groups,Positions of Large Groups,Easy,String,String832831,masking-personal-information,Masking Personal Information,Medium,String,String833832,flipping-an-image,Flipping an Image,Easy,Array;Two Pointers;Bit Manipulation;Matrix;Simulation,Array834833,find-and-replace-in-string,Find And Replace in String,Medium,Array;Hash Table;String;Sorting,Array835834,sum-of-distances-in-tree,Sum of Distances in Tree,Hard,Dynamic Programming;Tree;Depth-First Search;Graph Theory,Dynamic Programming836835,image-overlap,Image Overlap,Medium,Array;Matrix,Array837836,rectangle-overlap,Rectangle Overlap,Easy,Math;Geometry,Math838837,new-21-game,New 21 Game,Medium,Math;Dynamic Programming;Sliding Window;Probability and Statistics,Math839838,push-dominoes,Push Dominoes,Medium,Two Pointers;String;Dynamic Programming,Two Pointers840839,similar-string-groups,Similar String Groups,Hard,Array;Hash Table;String;Depth-First Search;Breadth-First Search;Union-Find,Array841840,magic-squares-in-grid,Magic Squares In Grid,Medium,Array;Hash Table;Math;Matrix,Array842841,keys-and-rooms,Keys and Rooms,Medium,Depth-First Search;Breadth-First Search;Graph Theory,Depth-First Search843842,split-array-into-fibonacci-sequence,Split Array into Fibonacci Sequence,Medium,String;Backtracking,String844843,guess-the-word,Guess the Word,Hard,Array;Math;String;Interactive;Game Theory,Array845844,backspace-string-compare,Backspace String Compare,Easy,Two Pointers;String;Stack;Simulation,Two Pointers846845,longest-mountain-in-array,Longest Mountain in Array,Medium,Array;Two Pointers;Dynamic Programming;Enumeration,Array847846,hand-of-straights,Hand of Straights,Medium,Array;Hash Table;Greedy;Sorting,Array848847,shortest-path-visiting-all-nodes,Shortest Path Visiting All Nodes,Hard,Dynamic Programming;Bit Manipulation;Breadth-First Search;Graph Theory;Bitmask,Dynamic Programming849848,shifting-letters,Shifting Letters,Medium,Array;String;Prefix Sum,Array850849,maximize-distance-to-closest-person,Maximize Distance to Closest Person,Medium,Array,Array851850,rectangle-area-ii,Rectangle Area II,Hard,Array;Segment Tree;Sweep Line;Ordered Set,Array852851,loud-and-rich,Loud and Rich,Medium,Array;Depth-First Search;Graph Theory;Topological Sort,Array853852,peak-index-in-a-mountain-array,Peak Index in a Mountain Array,Medium,Array;Binary Search,Array854853,car-fleet,Car Fleet,Medium,Array;Stack;Sorting;Monotonic Stack,Array855854,k-similar-strings,K-Similar Strings,Hard,Hash Table;String;Breadth-First Search,Hash Table856855,exam-room,Exam Room,Medium,Design;Heap (Priority Queue);Ordered Set,Design857856,score-of-parentheses,Score of Parentheses,Medium,String;Stack,String858857,minimum-cost-to-hire-k-workers,Minimum Cost to Hire K Workers,Hard,Array;Greedy;Sorting;Heap (Priority Queue),Array859858,mirror-reflection,Mirror Reflection,Medium,Math;Geometry;Number Theory,Math860859,buddy-strings,Buddy Strings,Easy,Hash Table;String,Hash Table861860,lemonade-change,Lemonade Change,Easy,Array;Greedy,Array862861,score-after-flipping-matrix,Score After Flipping Matrix,Medium,Array;Greedy;Bit Manipulation;Matrix,Array863862,shortest-subarray-with-sum-at-least-k,Shortest Subarray with Sum at Least K,Hard,Array;Binary Search;Queue;Sliding Window;Heap (Priority Queue);Prefix Sum;Monotonic Queue,Array864863,all-nodes-distance-k-in-binary-tree,All Nodes Distance K in Binary Tree,Medium,Hash Table;Tree;Depth-First Search;Breadth-First Search;Binary Tree,Hash Table865864,shortest-path-to-get-all-keys,Shortest Path to Get All Keys,Hard,Array;Bit Manipulation;Breadth-First Search;Matrix,Array866865,smallest-subtree-with-all-the-deepest-nodes,Smallest Subtree with all the Deepest Nodes,Medium,Hash Table;Tree;Depth-First Search;Breadth-First Search;Binary Tree,Hash Table867866,prime-palindrome,Prime Palindrome,Medium,Math;Number Theory,Math868867,transpose-matrix,Transpose Matrix,Easy,Array;Matrix;Simulation,Array869868,binary-gap,Binary Gap,Easy,Bit Manipulation,Bit Manipulation870869,reordered-power-of-2,Reordered Power of 2,Medium,Hash Table;Math;Sorting;Counting;Enumeration,Hash Table871870,advantage-shuffle,Advantage Shuffle,Medium,Array;Two Pointers;Greedy;Sorting,Array872871,minimum-number-of-refueling-stops,Minimum Number of Refueling Stops,Hard,Array;Dynamic Programming;Greedy;Heap (Priority Queue),Array873872,leaf-similar-trees,Leaf-Similar Trees,Easy,Tree;Depth-First Search;Binary Tree,Tree874873,length-of-longest-fibonacci-subsequence,Length of Longest Fibonacci Subsequence,Medium,Array;Hash Table;Dynamic Programming,Array875874,walking-robot-simulation,Walking Robot Simulation,Medium,Array;Hash Table;Simulation,Array876875,koko-eating-bananas,Koko Eating Bananas,Medium,Array;Binary Search,Array877876,middle-of-the-linked-list,Middle of the Linked List,Easy,Linked List;Two Pointers,Linked List878877,stone-game,Stone Game,Medium,Array;Math;Dynamic Programming;Game Theory,Array879878,nth-magical-number,Nth Magical Number,Hard,Math;Binary Search,Math880879,profitable-schemes,Profitable Schemes,Hard,Array;Dynamic Programming,Array881880,decoded-string-at-index,Decoded String at Index,Medium,String;Stack,String882881,boats-to-save-people,Boats to Save People,Medium,Array;Two Pointers;Greedy;Sorting,Array883882,reachable-nodes-in-subdivided-graph,Reachable Nodes In Subdivided Graph,Hard,Graph Theory;Heap (Priority Queue);Shortest Path,Graph Theory884883,projection-area-of-3d-shapes,Projection Area of 3D Shapes,Easy,Array;Math;Geometry;Matrix,Array885884,uncommon-words-from-two-sentences,Uncommon Words from Two Sentences,Easy,Hash Table;String;Counting,Hash Table886885,spiral-matrix-iii,Spiral Matrix III,Medium,Array;Matrix;Simulation,Array887886,possible-bipartition,Possible Bipartition,Medium,Depth-First Search;Breadth-First Search;Union-Find;Graph Theory,Depth-First Search888887,super-egg-drop,Super Egg Drop,Hard,Math;Binary Search;Dynamic Programming,Math889888,fair-candy-swap,Fair Candy Swap,Easy,Array;Hash Table;Binary Search;Sorting,Array890889,construct-binary-tree-from-preorder-and-postorder-traversal,Construct Binary Tree from Preorder and Postorder Traversal,Medium,Array;Hash Table;Divide and Conquer;Tree;Binary Tree,Array891890,find-and-replace-pattern,Find and Replace Pattern,Medium,Array;Hash Table;String,Array892891,sum-of-subsequence-widths,Sum of Subsequence Widths,Hard,Array;Math;Sorting,Array893892,surface-area-of-3d-shapes,Surface Area of 3D Shapes,Easy,Array;Math;Geometry;Matrix,Array894893,groups-of-special-equivalent-strings,Groups of Special-Equivalent Strings,Medium,Array;Hash Table;String;Sorting,Array895894,all-possible-full-binary-trees,All Possible Full Binary Trees,Medium,Dynamic Programming;Tree;Recursion;Memoization;Binary Tree,Dynamic Programming896895,maximum-frequency-stack,Maximum Frequency Stack,Hard,Hash Table;Stack;Design;Ordered Set,Hash Table897896,monotonic-array,Monotonic Array,Easy,Array,Array898897,increasing-order-search-tree,Increasing Order Search Tree,Easy,Stack;Tree;Depth-First Search;Binary Search Tree;Binary Tree,Stack899898,bitwise-ors-of-subarrays,Bitwise ORs of Subarrays,Medium,Array;Dynamic Programming;Bit Manipulation,Array900899,orderly-queue,Orderly Queue,Hard,Math;String;Sorting,Math901900,rle-iterator,RLE Iterator,Medium,Array;Design;Counting;Iterator,Array902901,online-stock-span,Online Stock Span,Medium,Stack;Design;Monotonic Stack;Data Stream,Stack903902,numbers-at-most-n-given-digit-set,Numbers At Most N Given Digit Set,Hard,Array;Math;String;Binary Search;Dynamic Programming,Array904903,valid-permutations-for-di-sequence,Valid Permutations for DI Sequence,Hard,String;Dynamic Programming;Prefix Sum,String905904,fruit-into-baskets,Fruit Into Baskets,Medium,Array;Hash Table;Sliding Window,Array906905,sort-array-by-parity,Sort Array By Parity,Easy,Array;Two Pointers;Sorting,Array907906,super-palindromes,Super Palindromes,Hard,Math;String;Enumeration,Math908907,sum-of-subarray-minimums,Sum of Subarray Minimums,Medium,Array;Dynamic Programming;Stack;Monotonic Stack,Array909908,smallest-range-i,Smallest Range I,Easy,Array;Math,Array910909,snakes-and-ladders,Snakes and Ladders,Medium,Array;Breadth-First Search;Matrix,Array911910,smallest-range-ii,Smallest Range II,Medium,Array;Math;Greedy;Sorting,Array912911,online-election,Online Election,Medium,Array;Hash Table;Binary Search;Design,Array913912,sort-an-array,Sort an Array,Medium,Array;Divide and Conquer;Sorting;Heap (Priority Queue);Merge Sort;Bucket Sort;Radix Sort;Counting Sort,Array914913,cat-and-mouse,Cat and Mouse,Hard,Math;Dynamic Programming;Graph Theory;Topological Sort;Memoization;Game Theory,Math915914,x-of-a-kind-in-a-deck-of-cards,X of a Kind in a Deck of Cards,Easy,Array;Hash Table;Math;Counting;Number Theory,Array916915,partition-array-into-disjoint-intervals,Partition Array into Disjoint Intervals,Medium,Array,Array917916,word-subsets,Word Subsets,Medium,Array;Hash Table;String,Array918917,reverse-only-letters,Reverse Only Letters,Easy,Two Pointers;String,Two Pointers919918,maximum-sum-circular-subarray,Maximum Sum Circular Subarray,Medium,Array;Divide and Conquer;Dynamic Programming;Queue;Monotonic Queue,Array920919,complete-binary-tree-inserter,Complete Binary Tree Inserter,Medium,Tree;Breadth-First Search;Design;Binary Tree,Tree921920,number-of-music-playlists,Number of Music Playlists,Hard,Math;Dynamic Programming;Combinatorics,Math922921,minimum-add-to-make-parentheses-valid,Minimum Add to Make Parentheses Valid,Medium,String;Stack;Greedy,String923922,sort-array-by-parity-ii,Sort Array By Parity II,Easy,Array;Two Pointers;Sorting,Array924923,3sum-with-multiplicity,3Sum With Multiplicity,Medium,Array;Hash Table;Two Pointers;Sorting;Counting,Array925924,minimize-malware-spread,Minimize Malware Spread,Hard,Array;Hash Table;Depth-First Search;Breadth-First Search;Union-Find;Graph Theory,Array926925,long-pressed-name,Long Pressed Name,Easy,Two Pointers;String,Two Pointers927926,flip-string-to-monotone-increasing,Flip String to Monotone Increasing,Medium,String;Dynamic Programming,String928927,three-equal-parts,Three Equal Parts,Hard,Array;Math,Array929928,minimize-malware-spread-ii,Minimize Malware Spread II,Hard,Array;Hash Table;Depth-First Search;Breadth-First Search;Union-Find;Graph Theory,Array930929,unique-email-addresses,Unique Email Addresses,Easy,Array;Hash Table;String,Array931930,binary-subarrays-with-sum,Binary Subarrays With Sum,Medium,Array;Hash Table;Sliding Window;Prefix Sum,Array932931,minimum-falling-path-sum,Minimum Falling Path Sum,Medium,Array;Dynamic Programming;Matrix,Array933932,beautiful-array,Beautiful Array,Medium,Array;Math;Divide and Conquer,Array934933,number-of-recent-calls,Number of Recent Calls,Easy,Design;Queue;Data Stream,Design935934,shortest-bridge,Shortest Bridge,Medium,Array;Depth-First Search;Breadth-First Search;Matrix,Array936935,knight-dialer,Knight Dialer,Medium,Dynamic Programming,Dynamic Programming937936,stamping-the-sequence,Stamping The Sequence,Hard,String;Stack;Greedy;Queue,String938937,reorder-data-in-log-files,Reorder Data in Log Files,Medium,Array;String;Sorting,Array939938,range-sum-of-bst,Range Sum of BST,Easy,Tree;Depth-First Search;Binary Search Tree;Binary Tree,Tree940939,minimum-area-rectangle,Minimum Area Rectangle,Medium,Array;Hash Table;Math;Geometry;Sorting,Array941940,distinct-subsequences-ii,Distinct Subsequences II,Hard,String;Dynamic Programming,String942941,valid-mountain-array,Valid Mountain Array,Easy,Array,Array943942,di-string-match,DI String Match,Easy,Array;Two Pointers;String;Greedy,Array944943,find-the-shortest-superstring,Find the Shortest Superstring,Hard,Array;String;Dynamic Programming;Bit Manipulation;Bitmask,Array945944,delete-columns-to-make-sorted,Delete Columns to Make Sorted,Easy,Array;String,Array946945,minimum-increment-to-make-array-unique,Minimum Increment to Make Array Unique,Medium,Array;Greedy;Sorting;Counting,Array947946,validate-stack-sequences,Validate Stack Sequences,Medium,Array;Stack;Simulation,Array948947,most-stones-removed-with-same-row-or-column,Most Stones Removed with Same Row or Column,Medium,Hash Table;Depth-First Search;Union-Find;Graph Theory,Hash Table949948,bag-of-tokens,Bag of Tokens,Medium,Array;Two Pointers;Greedy;Sorting,Array950949,largest-time-for-given-digits,Largest Time for Given Digits,Medium,Array;String;Backtracking;Enumeration,Array951950,reveal-cards-in-increasing-order,Reveal Cards In Increasing Order,Medium,Array;Queue;Sorting;Simulation,Array952951,flip-equivalent-binary-trees,Flip Equivalent Binary Trees,Medium,Tree;Depth-First Search;Binary Tree,Tree953952,largest-component-size-by-common-factor,Largest Component Size by Common Factor,Hard,Array;Hash Table;Math;Union-Find;Number Theory,Array954953,verifying-an-alien-dictionary,Verifying an Alien Dictionary,Easy,Array;Hash Table;String,Array955954,array-of-doubled-pairs,Array of Doubled Pairs,Medium,Array;Hash Table;Greedy;Sorting,Array956955,delete-columns-to-make-sorted-ii,Delete Columns to Make Sorted II,Medium,Array;String;Greedy,Array957956,tallest-billboard,Tallest Billboard,Hard,Array;Dynamic Programming,Array958957,prison-cells-after-n-days,Prison Cells After N Days,Medium,Array;Hash Table;Math;Bit Manipulation,Array959958,check-completeness-of-a-binary-tree,Check Completeness of a Binary Tree,Medium,Tree;Breadth-First Search;Binary Tree,Tree960959,regions-cut-by-slashes,Regions Cut By Slashes,Medium,Array;Hash Table;Depth-First Search;Breadth-First Search;Union-Find;Matrix,Array961960,delete-columns-to-make-sorted-iii,Delete Columns to Make Sorted III,Hard,Array;String;Dynamic Programming,Array962961,n-repeated-element-in-size-2n-array,N-Repeated Element in Size 2N Array,Easy,Array;Hash Table,Array963962,maximum-width-ramp,Maximum Width Ramp,Medium,Array;Two Pointers;Stack;Monotonic Stack,Array964963,minimum-area-rectangle-ii,Minimum Area Rectangle II,Medium,Array;Hash Table;Math;Geometry,Array965964,least-operators-to-express-number,Least Operators to Express Number,Hard,Math;Dynamic Programming;Memoization,Math966965,univalued-binary-tree,Univalued Binary Tree,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree967966,vowel-spellchecker,Vowel Spellchecker,Medium,Array;Hash Table;String,Array968967,numbers-with-same-consecutive-differences,Numbers With Same Consecutive Differences,Medium,Backtracking;Breadth-First Search,Backtracking969968,binary-tree-cameras,Binary Tree Cameras,Hard,Dynamic Programming;Tree;Depth-First Search;Binary Tree,Dynamic Programming970969,pancake-sorting,Pancake Sorting,Medium,Array;Two Pointers;Greedy;Sorting,Array971970,powerful-integers,Powerful Integers,Medium,Hash Table;Math;Enumeration,Hash Table972971,flip-binary-tree-to-match-preorder-traversal,Flip Binary Tree To Match Preorder Traversal,Medium,Tree;Depth-First Search;Binary Tree,Tree973972,equal-rational-numbers,Equal Rational Numbers,Hard,Math;String,Math974973,k-closest-points-to-origin,K Closest Points to Origin,Medium,Array;Math;Divide and Conquer;Geometry;Sorting;Heap (Priority Queue);Quickselect,Array975974,subarray-sums-divisible-by-k,Subarray Sums Divisible by K,Medium,Array;Hash Table;Prefix Sum,Array976975,odd-even-jump,Odd Even Jump,Hard,Array;Dynamic Programming;Stack;Sorting;Monotonic Stack;Ordered Set,Array977976,largest-perimeter-triangle,Largest Perimeter Triangle,Easy,Array;Math;Greedy;Sorting,Array978977,squares-of-a-sorted-array,Squares of a Sorted Array,Easy,Array;Two Pointers;Sorting,Array979978,longest-turbulent-subarray,Longest Turbulent Subarray,Medium,Array;Dynamic Programming;Sliding Window,Array980979,distribute-coins-in-binary-tree,Distribute Coins in Binary Tree,Medium,Tree;Depth-First Search;Binary Tree,Tree981980,unique-paths-iii,Unique Paths III,Hard,Array;Backtracking;Bit Manipulation;Matrix,Array982981,time-based-key-value-store,Time Based Key-Value Store,Medium,Hash Table;String;Binary Search;Design,Hash Table983982,triples-with-bitwise-and-equal-to-zero,Triples with Bitwise AND Equal To Zero,Hard,Array;Hash Table;Bit Manipulation,Array984983,minimum-cost-for-tickets,Minimum Cost For Tickets,Medium,Array;Dynamic Programming,Array985984,string-without-aaa-or-bbb,String Without AAA or BBB,Medium,String;Greedy,String986985,sum-of-even-numbers-after-queries,Sum of Even Numbers After Queries,Medium,Array;Simulation,Array987986,interval-list-intersections,Interval List Intersections,Medium,Array;Two Pointers;Sweep Line,Array988987,vertical-order-traversal-of-a-binary-tree,Vertical Order Traversal of a Binary Tree,Hard,Hash Table;Tree;Depth-First Search;Breadth-First Search;Sorting;Binary Tree,Hash Table989988,smallest-string-starting-from-leaf,Smallest String Starting From Leaf,Medium,String;Backtracking;Tree;Depth-First Search;Binary Tree,String990989,add-to-array-form-of-integer,Add to Array-Form of Integer,Easy,Array;Math,Array991990,satisfiability-of-equality-equations,Satisfiability of Equality Equations,Medium,Array;String;Union-Find;Graph Theory,Array992991,broken-calculator,Broken Calculator,Medium,Math;Greedy,Math993992,subarrays-with-k-different-integers,Subarrays with K Different Integers,Hard,Array;Hash Table;Sliding Window;Counting,Array994993,cousins-in-binary-tree,Cousins in Binary Tree,Easy,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree995994,rotting-oranges,Rotting Oranges,Medium,Array;Breadth-First Search;Matrix,Array996995,minimum-number-of-k-consecutive-bit-flips,Minimum Number of K Consecutive Bit Flips,Hard,Array;Bit Manipulation;Queue;Sliding Window;Prefix Sum,Array997996,number-of-squareful-arrays,Number of Squareful Arrays,Hard,Array;Hash Table;Math;Dynamic Programming;Backtracking;Bit Manipulation;Bitmask,Array998997,find-the-town-judge,Find the Town Judge,Easy,Array;Hash Table;Graph Theory,Array999998,maximum-binary-tree-ii,Maximum Binary Tree II,Medium,Tree;Binary Tree,Tree1000999,available-captures-for-rook,Available Captures for Rook,Easy,Array;Matrix;Simulation,Array10011000,minimum-cost-to-merge-stones,Minimum Cost to Merge Stones,Hard,Array;Dynamic Programming;Prefix Sum,Array10021001,grid-illumination,Grid Illumination,Hard,Array;Hash Table,Array10031002,find-common-characters,Find Common Characters,Easy,Array;Hash Table;String,Array10041003,check-if-word-is-valid-after-substitutions,Check If Word Is Valid After Substitutions,Medium,String;Stack,String10051004,max-consecutive-ones-iii,Max Consecutive Ones III,Medium,Array;Binary Search;Sliding Window;Prefix Sum,Array10061005,maximize-sum-of-array-after-k-negations,Maximize Sum Of Array After K Negations,Easy,Array;Greedy;Sorting,Array10071006,clumsy-factorial,Clumsy Factorial,Medium,Math;Stack;Simulation,Math10081007,minimum-domino-rotations-for-equal-row,Minimum Domino Rotations For Equal Row,Medium,Array;Greedy,Array10091008,construct-binary-search-tree-from-preorder-traversal,Construct Binary Search Tree from Preorder Traversal,Medium,Array;Stack;Tree;Binary Search Tree;Monotonic Stack;Binary Tree,Array10101009,complement-of-base-10-integer,Complement of Base 10 Integer,Easy,Bit Manipulation,Bit Manipulation10111010,pairs-of-songs-with-total-durations-divisible-by-60,Pairs of Songs With Total Durations Divisible by 60,Medium,Array;Hash Table;Counting,Array10121011,capacity-to-ship-packages-within-d-days,Capacity To Ship Packages Within D Days,Medium,Array;Binary Search,Array10131012,numbers-with-repeated-digits,Numbers With Repeated Digits,Hard,Math;Dynamic Programming,Math10141013,partition-array-into-three-parts-with-equal-sum,Partition Array Into Three Parts With Equal Sum,Easy,Array;Greedy,Array10151014,best-sightseeing-pair,Best Sightseeing Pair,Medium,Array;Dynamic Programming,Array10161015,smallest-integer-divisible-by-k,Smallest Integer Divisible by K,Medium,Hash Table;Math,Hash Table10171016,binary-string-with-substrings-representing-1-to-n,Binary String With Substrings Representing 1 To N,Medium,Hash Table;String;Bit Manipulation;Sliding Window,Hash Table10181017,convert-to-base-2,Convert to Base -2,Medium,Math,Math10191018,binary-prefix-divisible-by-5,Binary Prefix Divisible By 5,Easy,Array;Bit Manipulation,Array10201019,next-greater-node-in-linked-list,Next Greater Node In Linked List,Medium,Array;Linked List;Stack;Monotonic Stack,Array10211020,number-of-enclaves,Number of Enclaves,Medium,Array;Depth-First Search;Breadth-First Search;Union-Find;Matrix,Array10221021,remove-outermost-parentheses,Remove Outermost Parentheses,Easy,String;Stack,String10231022,sum-of-root-to-leaf-binary-numbers,Sum of Root To Leaf Binary Numbers,Easy,Tree;Depth-First Search;Binary Tree,Tree10241023,camelcase-matching,Camelcase Matching,Medium,Array;Two Pointers;String;Trie;String Matching,Array10251024,video-stitching,Video Stitching,Medium,Array;Dynamic Programming;Greedy,Array10261025,divisor-game,Divisor Game,Easy,Math;Dynamic Programming;Brainteaser;Game Theory,Math10271026,maximum-difference-between-node-and-ancestor,Maximum Difference Between Node and Ancestor,Medium,Tree;Depth-First Search;Binary Tree,Tree10281027,longest-arithmetic-subsequence,Longest Arithmetic Subsequence,Medium,Array;Hash Table;Binary Search;Dynamic Programming,Array10291028,recover-a-tree-from-preorder-traversal,Recover a Tree From Preorder Traversal,Hard,String;Tree;Depth-First Search;Binary Tree,String10301029,two-city-scheduling,Two City Scheduling,Medium,Array;Greedy;Sorting,Array10311030,matrix-cells-in-distance-order,Matrix Cells in Distance Order,Easy,Array;Math;Geometry;Sorting;Matrix,Array10321031,maximum-sum-of-two-non-overlapping-subarrays,Maximum Sum of Two Non-Overlapping Subarrays,Medium,Array;Dynamic Programming;Sliding Window,Array10331032,stream-of-characters,Stream of Characters,Hard,Array;String;Design;Trie;Data Stream,Array10341033,moving-stones-until-consecutive,Moving Stones Until Consecutive,Medium,Math;Brainteaser,Math10351034,coloring-a-border,Coloring A Border,Medium,Array;Depth-First Search;Breadth-First Search;Matrix,Array10361035,uncrossed-lines,Uncrossed Lines,Medium,Array;Dynamic Programming,Array10371036,escape-a-large-maze,Escape a Large Maze,Hard,Array;Hash Table;Depth-First Search;Breadth-First Search,Array10381037,valid-boomerang,Valid Boomerang,Easy,Array;Math;Geometry,Array10391038,binary-search-tree-to-greater-sum-tree,Binary Search Tree to Greater Sum Tree,Medium,Tree;Depth-First Search;Binary Search Tree;Binary Tree,Tree10401039,minimum-score-triangulation-of-polygon,Minimum Score Triangulation of Polygon,Medium,Array;Dynamic Programming,Array10411040,moving-stones-until-consecutive-ii,Moving Stones Until Consecutive II,Medium,Array;Math;Sliding Window;Sorting,Array10421041,robot-bounded-in-circle,Robot Bounded In Circle,Medium,Math;String;Simulation,Math10431042,flower-planting-with-no-adjacent,Flower Planting With No Adjacent,Medium,Depth-First Search;Breadth-First Search;Graph Theory,Depth-First Search10441043,partition-array-for-maximum-sum,Partition Array for Maximum Sum,Medium,Array;Dynamic Programming,Array10451044,longest-duplicate-substring,Longest Duplicate Substring,Hard,String;Binary Search;Sliding Window;Rolling Hash;Suffix Array;Hash Function,String10461045,customers-who-bought-all-products,Customers Who Bought All Products,Medium,Database,Database10471046,last-stone-weight,Last Stone Weight,Easy,Array;Heap (Priority Queue),Array10481047,remove-all-adjacent-duplicates-in-string,Remove All Adjacent Duplicates In String,Easy,String;Stack,String10491048,longest-string-chain,Longest String Chain,Medium,Array;Hash Table;Two Pointers;String;Dynamic Programming;Sorting,Array10501049,last-stone-weight-ii,Last Stone Weight II,Medium,Array;Dynamic Programming,Array10511050,actors-and-directors-who-cooperated-at-least-three-times,Actors and Directors Who Cooperated At Least Three Times,Easy,Database,Database10521051,height-checker,Height Checker,Easy,Array;Sorting;Counting Sort,Array10531052,grumpy-bookstore-owner,Grumpy Bookstore Owner,Medium,Array;Sliding Window,Array10541053,previous-permutation-with-one-swap,Previous Permutation With One Swap,Medium,Array;Greedy,Array10551054,distant-barcodes,Distant Barcodes,Medium,Array;Hash Table;Greedy;Sorting;Heap (Priority Queue);Counting,Array10561055,shortest-way-to-form-string,Shortest Way to Form String,Medium,Two Pointers;String;Binary Search;Greedy,Two Pointers10571056,confusing-number,Confusing Number,Easy,Math,Math10581057,campus-bikes,Campus Bikes,Medium,Array;Sorting;Heap (Priority Queue),Array10591058,minimize-rounding-error-to-meet-target,Minimize Rounding Error to Meet Target,Medium,Array;Math;String;Greedy;Sorting,Array10601059,all-paths-from-source-lead-to-destination,All Paths from Source Lead to Destination,Medium,Graph Theory;Topological Sort,Graph Theory10611060,missing-element-in-sorted-array,Missing Element in Sorted Array,Medium,Array;Binary Search,Array10621061,lexicographically-smallest-equivalent-string,Lexicographically Smallest Equivalent String,Medium,String;Union-Find,String10631062,longest-repeating-substring,Longest Repeating Substring,Medium,String;Binary Search;Dynamic Programming;Rolling Hash;Suffix Array;Hash Function,String10641063,number-of-valid-subarrays,Number of Valid Subarrays,Hard,Array;Stack;Monotonic Stack,Array10651064,fixed-point,Fixed Point,Easy,Array;Binary Search,Array10661065,index-pairs-of-a-string,Index Pairs of a String,Easy,Array;String;Trie;Sorting,Array10671066,campus-bikes-ii,Campus Bikes II,Medium,Array;Dynamic Programming;Backtracking;Bit Manipulation;Bitmask,Array10681067,digit-count-in-range,Digit Count in Range,Hard,Math;Dynamic Programming,Math10691068,product-sales-analysis-i,Product Sales Analysis I,Easy,Database,Database10701069,product-sales-analysis-ii,Product Sales Analysis II,Easy,Database,Database10711070,product-sales-analysis-iii,Product Sales Analysis III,Medium,Database,Database10721071,greatest-common-divisor-of-strings,Greatest Common Divisor of Strings,Easy,Math;String,Math10731072,flip-columns-for-maximum-number-of-equal-rows,Flip Columns For Maximum Number of Equal Rows,Medium,Array;Hash Table;Matrix,Array10741073,adding-two-negabinary-numbers,Adding Two Negabinary Numbers,Medium,Array;Math,Array10751074,number-of-submatrices-that-sum-to-target,Number of Submatrices That Sum to Target,Hard,Array;Hash Table;Matrix;Prefix Sum,Array10761075,project-employees-i,Project Employees I,Easy,Database,Database10771076,project-employees-ii,Project Employees II,Easy,Database,Database10781077,project-employees-iii,Project Employees III,Medium,Database,Database10791078,occurrences-after-bigram,Occurrences After Bigram,Easy,String,String10801079,letter-tile-possibilities,Letter Tile Possibilities,Medium,Hash Table;String;Backtracking;Counting,Hash Table10811080,insufficient-nodes-in-root-to-leaf-paths,Insufficient Nodes in Root to Leaf Paths,Medium,Tree;Depth-First Search;Binary Tree,Tree10821081,smallest-subsequence-of-distinct-characters,Smallest Subsequence of Distinct Characters,Medium,String;Stack;Greedy;Monotonic Stack,String10831082,sales-analysis-i,Sales Analysis I,Easy,Database,Database10841083,sales-analysis-ii,Sales Analysis II,Easy,Database,Database10851084,sales-analysis-iii,Sales Analysis III,Easy,Database,Database10861085,sum-of-digits-in-the-minimum-number,Sum of Digits in the Minimum Number,Easy,Array;Math,Array10871086,high-five,High Five,Easy,Array;Hash Table;Sorting;Heap (Priority Queue),Array10881087,brace-expansion,Brace Expansion,Medium,String;Backtracking;Stack;Breadth-First Search;Sorting,String10891088,confusing-number-ii,Confusing Number II,Hard,Math;Backtracking,Math10901089,duplicate-zeros,Duplicate Zeros,Easy,Array;Two Pointers,Array10911090,largest-values-from-labels,Largest Values From Labels,Medium,Array;Hash Table;Greedy;Sorting;Counting,Array10921091,shortest-path-in-binary-matrix,Shortest Path in Binary Matrix,Medium,Array;Breadth-First Search;Matrix,Array10931092,shortest-common-supersequence,Shortest Common Supersequence ,Hard,String;Dynamic Programming,String10941093,statistics-from-a-large-sample,Statistics from a Large Sample,Medium,Array;Math;Probability and Statistics,Array10951094,car-pooling,Car Pooling,Medium,Array;Sorting;Heap (Priority Queue);Simulation;Prefix Sum,Array10961095,find-in-mountain-array,Find in Mountain Array,Hard,Array;Binary Search;Interactive,Array10971096,brace-expansion-ii,Brace Expansion II,Hard,Hash Table;String;Backtracking;Stack;Breadth-First Search;Sorting,Hash Table10981097,game-play-analysis-v,Game Play Analysis V,Hard,Database,Database10991098,unpopular-books,Unpopular Books,Medium,Database,Database11001099,two-sum-less-than-k,Two Sum Less Than K,Easy,Array;Two Pointers;Binary Search;Sorting,Array11011100,find-k-length-substrings-with-no-repeated-characters,Find K-Length Substrings With No Repeated Characters,Medium,Hash Table;String;Sliding Window,Hash Table11021101,the-earliest-moment-when-everyone-become-friends,The Earliest Moment When Everyone Become Friends,Medium,Array;Union-Find;Sorting,Array11031102,path-with-maximum-minimum-value,Path With Maximum Minimum Value,Medium,Array;Binary Search;Depth-First Search;Breadth-First Search;Union-Find;Heap (Priority Queue);Matrix,Array11041103,distribute-candies-to-people,Distribute Candies to People,Easy,Math;Simulation,Math11051104,path-in-zigzag-labelled-binary-tree,Path In Zigzag Labelled Binary Tree,Medium,Math;Tree;Binary Tree,Math11061105,filling-bookcase-shelves,Filling Bookcase Shelves,Medium,Array;Dynamic Programming,Array11071106,parsing-a-boolean-expression,Parsing A Boolean Expression,Hard,String;Stack;Recursion,String11081107,new-users-daily-count,New Users Daily Count,Medium,Database,Database11091108,defanging-an-ip-address,Defanging an IP Address,Easy,String,String11101109,corporate-flight-bookings,Corporate Flight Bookings,Medium,Array;Prefix Sum,Array11111110,delete-nodes-and-return-forest,Delete Nodes And Return Forest,Medium,Array;Hash Table;Tree;Depth-First Search;Binary Tree,Array11121111,maximum-nesting-depth-of-two-valid-parentheses-strings,Maximum Nesting Depth of Two Valid Parentheses Strings,Medium,String;Stack,String11131112,highest-grade-for-each-student,Highest Grade For Each Student,Medium,Database,Database11141113,reported-posts,Reported Posts,Easy,Database,Database11151114,print-in-order,Print in Order,Easy,Concurrency,Concurrency11161115,print-foobar-alternately,Print FooBar Alternately,Medium,Concurrency,Concurrency11171116,print-zero-even-odd,Print Zero Even Odd,Medium,Concurrency,Concurrency11181117,building-h2o,Building H2O,Medium,Concurrency,Concurrency11191118,number-of-days-in-a-month,Number of Days in a Month,Easy,Math,Math11201119,remove-vowels-from-a-string,Remove Vowels from a String,Easy,String,String11211120,maximum-average-subtree,Maximum Average Subtree,Medium,Tree;Depth-First Search;Binary Tree,Tree11221121,divide-array-into-increasing-sequences,Divide Array Into Increasing Sequences,Hard,Array;Counting,Array11231122,relative-sort-array,Relative Sort Array,Easy,Array;Hash Table;Sorting;Counting Sort,Array11241123,lowest-common-ancestor-of-deepest-leaves,Lowest Common Ancestor of Deepest Leaves,Medium,Hash Table;Tree;Depth-First Search;Breadth-First Search;Binary Tree,Hash Table11251124,longest-well-performing-interval,Longest Well-Performing Interval,Medium,Array;Hash Table;Stack;Monotonic Stack;Prefix Sum,Array11261125,smallest-sufficient-team,Smallest Sufficient Team,Hard,Array;Dynamic Programming;Bit Manipulation;Bitmask,Array11271126,active-businesses,Active Businesses,Medium,Database,Database11281127,user-purchase-platform,User Purchase Platform,Hard,Database,Database11291128,number-of-equivalent-domino-pairs,Number of Equivalent Domino Pairs,Easy,Array;Hash Table;Counting,Array11301129,shortest-path-with-alternating-colors,Shortest Path with Alternating Colors,Medium,Breadth-First Search;Graph Theory,Breadth-First Search11311130,minimum-cost-tree-from-leaf-values,Minimum Cost Tree From Leaf Values,Medium,Array;Dynamic Programming;Stack;Greedy;Monotonic Stack,Array11321131,maximum-of-absolute-value-expression,Maximum of Absolute Value Expression,Medium,Array;Math,Array11331132,reported-posts-ii,Reported Posts II,Medium,Database,Database11341133,largest-unique-number,Largest Unique Number,Easy,Array;Hash Table;Sorting,Array11351134,armstrong-number,Armstrong Number,Easy,Math,Math11361135,connecting-cities-with-minimum-cost,Connecting Cities With Minimum Cost,Medium,Union-Find;Graph Theory;Heap (Priority Queue);Minimum Spanning Tree,Union-Find11371136,parallel-courses,Parallel Courses,Medium,Graph Theory;Topological Sort,Graph Theory11381137,n-th-tribonacci-number,N-th Tribonacci Number,Easy,Math;Dynamic Programming;Memoization,Math11391138,alphabet-board-path,Alphabet Board Path,Medium,Hash Table;String,Hash Table11401139,largest-1-bordered-square,Largest 1-Bordered Square,Medium,Array;Dynamic Programming;Matrix,Array11411140,stone-game-ii,Stone Game II,Medium,Array;Math;Dynamic Programming;Prefix Sum;Game Theory,Array11421141,user-activity-for-the-past-30-days-i,User Activity for the Past 30 Days I,Easy,Database,Database11431142,user-activity-for-the-past-30-days-ii,User Activity for the Past 30 Days II,Easy,Database,Database11441143,longest-common-subsequence,Longest Common Subsequence,Medium,String;Dynamic Programming,String11451144,decrease-elements-to-make-array-zigzag,Decrease Elements To Make Array Zigzag,Medium,Array;Greedy,Array11461145,binary-tree-coloring-game,Binary Tree Coloring Game,Medium,Tree;Depth-First Search;Binary Tree,Tree11471146,snapshot-array,Snapshot Array,Medium,Array;Hash Table;Binary Search;Design,Array11481147,longest-chunked-palindrome-decomposition,Longest Chunked Palindrome Decomposition,Hard,Two Pointers;String;Dynamic Programming;Greedy;Rolling Hash;Hash Function,Two Pointers11491148,article-views-i,Article Views I,Easy,Database,Database11501149,article-views-ii,Article Views II,Medium,Database,Database11511150,check-if-a-number-is-majority-element-in-a-sorted-array,Check If a Number Is Majority Element in a Sorted Array,Easy,Array;Binary Search,Array11521151,minimum-swaps-to-group-all-1s-together,Minimum Swaps to Group All 1's Together,Medium,Array;Sliding Window,Array11531152,analyze-user-website-visit-pattern,Analyze User Website Visit Pattern,Medium,Array;Hash Table;String;Sorting,Array11541153,string-transforms-into-another-string,String Transforms Into Another String,Hard,Hash Table;String;Graph Theory,Hash Table11551154,day-of-the-year,Day of the Year,Easy,Math;String,Math11561155,number-of-dice-rolls-with-target-sum,Number of Dice Rolls With Target Sum,Medium,Dynamic Programming,Dynamic Programming11571156,swap-for-longest-repeated-character-substring,Swap For Longest Repeated Character Substring,Medium,Hash Table;String;Sliding Window,Hash Table11581157,online-majority-element-in-subarray,Online Majority Element In Subarray,Hard,Array;Binary Search;Design;Binary Indexed Tree;Segment Tree,Array11591158,market-analysis-i,Market Analysis I,Medium,Database,Database11601159,market-analysis-ii,Market Analysis II,Hard,Database,Database11611160,find-words-that-can-be-formed-by-characters,Find Words That Can Be Formed by Characters,Easy,Array;Hash Table;String;Counting,Array11621161,maximum-level-sum-of-a-binary-tree,Maximum Level Sum of a Binary Tree,Medium,Tree;Depth-First Search;Breadth-First Search;Binary Tree,Tree11631162,as-far-from-land-as-possible,As Far from Land as Possible,Medium,Array;Dynamic Programming;Breadth-First Search;Matrix,Array11641163,last-substring-in-lexicographical-order,Last Substring in Lexicographical Order,Hard,Two Pointers;String,Two Pointers11651164,product-price-at-a-given-date,Product Price at a Given Date,Medium,Database,Database11661165,single-row-keyboard,Single-Row Keyboard,Easy,Hash Table;String,Hash Table11671166,design-file-system,Design File System,Medium,Hash Table;String;Design;Trie,Hash Table11681167,minimum-cost-to-connect-sticks,Minimum Cost to Connect Sticks,Medium,Array;Greedy;Heap (Priority Queue),Array11691168,optimize-water-distribution-in-a-village,Optimize Water Distribution in a Village,Hard,Union-Find;Graph Theory;Heap (Priority Queue);Minimum Spanning Tree,Union-Find11701169,invalid-transactions,Invalid Transactions,Medium,Array;Hash Table;String;Sorting,Array11711170,compare-strings-by-frequency-of-the-smallest-character,Compare Strings by Frequency of the Smallest Character,Medium,Array;Hash Table;String;Binary Search;Sorting,Array11721171,remove-zero-sum-consecutive-nodes-from-linked-list,Remove Zero Sum Consecutive Nodes from Linked List,Medium,Hash Table;Linked List,Hash Table11731172,dinner-plate-stacks,Dinner Plate Stacks,Hard,Hash Table;Stack;Design;Heap (Priority Queue),Hash Table11741173,immediate-food-delivery-i,Immediate Food Delivery I,Easy,Database,Database11751174,immediate-food-delivery-ii,Immediate Food Delivery II,Medium,Database,Database11761175,prime-arrangements,Prime Arrangements,Easy,Math,Math11771176,diet-plan-performance,Diet Plan Performance,Easy,Array;Sliding Window,Array11781177,can-make-palindrome-from-substring,Can Make Palindrome from Substring,Medium,Array;Hash Table;String;Bit Manipulation;Prefix Sum,Array11791178,number-of-valid-words-for-each-puzzle,Number of Valid Words for Each Puzzle,Hard,Array;Hash Table;String;Bit Manipulation;Trie,Array11801179,reformat-department-table,Reformat Department Table,Easy,Database,Database11811180,count-substrings-with-only-one-distinct-letter,Count Substrings with Only One Distinct Letter,Easy,Math;String,Math11821181,before-and-after-puzzle,Before and After Puzzle,Medium,Array;Hash Table;String;Sorting,Array11831182,shortest-distance-to-target-color,Shortest Distance to Target Color,Medium,Array;Binary Search;Dynamic Programming,Array11841183,maximum-number-of-ones,Maximum Number of Ones,Hard,Math;Greedy;Sorting;Heap (Priority Queue),Math11851184,distance-between-bus-stops,Distance Between Bus Stops,Easy,Array,Array11861185,day-of-the-week,Day of the Week,Easy,Math,Math11871186,maximum-subarray-sum-with-one-deletion,Maximum Subarray Sum with One Deletion,Medium,Array;Dynamic Programming,Array11881187,make-array-strictly-increasing,Make Array Strictly Increasing,Hard,Array;Binary Search;Dynamic Programming;Sorting,Array11891188,design-bounded-blocking-queue,Design Bounded Blocking Queue,Medium,Concurrency,Concurrency11901189,maximum-number-of-balloons,Maximum Number of Balloons,Easy,Hash Table;String;Counting,Hash Table11911190,reverse-substrings-between-each-pair-of-parentheses,Reverse Substrings Between Each Pair of Parentheses,Medium,String;Stack,String11921191,k-concatenation-maximum-sum,K-Concatenation Maximum Sum,Medium,Array;Dynamic Programming,Array11931192,critical-connections-in-a-network,Critical Connections in a Network,Hard,Depth-First Search;Graph Theory;Biconnected Component,Depth-First Search11941193,monthly-transactions-i,Monthly Transactions I,Medium,Database,Database11951194,tournament-winners,Tournament Winners,Hard,Database,Database11961195,fizz-buzz-multithreaded,Fizz Buzz Multithreaded,Medium,Concurrency,Concurrency11971196,how-many-apples-can-you-put-into-the-basket,How Many Apples Can You Put into the Basket,Easy,Array;Greedy;Sorting,Array11981197,minimum-knight-moves,Minimum Knight Moves,Medium,Breadth-First Search,Breadth-First Search11991198,find-smallest-common-element-in-all-rows,Find Smallest Common Element in All Rows,Medium,Array;Hash Table;Binary Search;Matrix;Counting,Array12001199,minimum-time-to-build-blocks,Minimum Time to Build Blocks,Hard,Array;Math;Greedy;Heap (Priority Queue),Array

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