Practice of Algorithm Problems
  • Main
  • Array
    • 1. Two Sum
    • 11. Container With Most Water
    • 15. 3Sum
    • 16. 3Sum Closest
    • 18. 4Sum
    • 26. Remove Duplicates from Sorted Array
    • 27. Remove Element
    • 31. Next Permutation
    • 36. Valid Sudoku
    • 41. First Missing Positive
    • 42. Trapping Rain Water
    • 48. Rotate Image
    • 54. Spiral Matrix
    • 56. Merge Intervals
    • 57. Insert Interval
    • 59. Spiral Matrix II
    • 66. Plus One
    • 73. Set Matrix Zeroes
    • 75. Sort Colors
    • 80. Remove Duplicates from Sorted Array II
    • 88. Merge Sorted Array
    • 118. Pascal's Triangle
    • 119. Pascal's Triangle II
    • 121. Best Time to Buy and Sell Stock
    • 122. Best Time to Buy and Sell Stock II
    • 123. Best Time to Buy and Sell Stock III
    • 128. Longest Consecutive Sequence
    • 163. Missing Ranges
    • 164. Maximum Gap
    • 167. Two Sum II - Input array is sorted
    • 169. Majority Element
    • 188. Best Time to Buy and Sell Stock IV
    • 189. Rotate Array
    • 200. Number of Islands
    • 209. Minimum Size Subarray Sum
    • 217. Contains Duplicate
    • 219. Contains Duplicate II
    • 220. Contains Duplicate III
    • 228. Summary Ranges
    • 229. Majority Element II
    • 238. Product of Array Except Self
    • 239. Sliding Window Maximum
    • 243. Shortest Word Distance
    • 244. Shortest Word Distance II
    • 245. Shortest Word Distance III
    • 252. Meeting Rooms
    • 253. Meeting Rooms II
    • 259. 3Sum Smaller
    • 268. Missing Number
    • 277. Find the Celebrity
    • 280. Wiggle Sort
    • 283. Move Zeroes
    • 287. Find the Duplicate Number
    • 289. Game of Life
    • 299. Bulls and Cows
    • 307. Range Sum Query - Mutable
    • 308. Range Sum Query 2D - Mutable
    • 309. Best Time to Buy and Sell Stock with Cooldown
    • 311. Sparse Matrix Multiplication
    • 324. Wiggle Sort II
    • 325. Maximum Size Subarray Sum Equals k
    • 334. Increasing Triplet Subsequence
    • 370. Range Addition
    • 414. Third Maximum Number
    • 419. Battleships in a Board
    • 442. Find All Duplicates in an Array
    • 448. Find All Numbers Disappeared in an Array
    • 454. 4Sum II
    • 457. Circular Array Loop
    • 463. Island Perimeter
    • 480. Sliding Window Median
    • 485. Max Consecutive Ones
    • 487. Max Consecutive Ones II
    • 495. Teemo Attacking
    • 498. Diagonal Traverse
    • 509. Fibonacci Number
    • 523. Continuous Subarray Sum
    • 525. Contiguous Array
    • 531. Lonely Pixel I
    • 533. Lonely Pixel II
    • 548. Split Array with Equal Sum
    • 560. Subarray Sum Equals K
    • 561. Array Partition I
    • 562. Longest Line of Consecutive One in Matrix
    • 565. Array Nesting
    • 566. Reshape the Matrix
    • 587. Erect the Fence
    • 605. Can Place Flowers
    • 611. Valid Triangle Number
    • 624. Maximum Distance in Arrays
    • 643. Maximum Average Subarray I
    • 644. Maximum Average Subarray II
    • 645. Set Mismatch
    • 649. Dota2 Senate
    • 670. Maximum Swap
    • 695. Max Area of Island
    • 697. Degree of an Array
    • 713. Subarray Product Less Than K
    • 714. Best Time to Buy and Sell Stock with Transaction Fee
    • 717. 1-bit and 2-bit Characters
    • 724. Find Pivot Index
    • 768. Max Chunks To Make Sorted II
    • 769. Max Chunks To Make Sorted
    • 792. Number of Matching Subsequences
    • 849. Maximize Distance to Closest Person
    • 855. Exam Room
    • 862. Shortest Subarray with Sum at Least K
    • 904. Fruit Into Baskets
    • 905. Sort Array By Parity
    • 930. Binary Subarrays With Sum
    • 939. Minimum Area Rectangle
    • 957. Prison Cells After N Days
    • 974. Subarray Sums Divisible by K
    • 977. Squares of a Sorted Array
    • 989. Add to Array-Form of Integer
    • 992. Subarrays with K Different Integers
    • 997. Find the Town Judge
    • 1002. Find Common Characters
    • 1004. Max Consecutive Ones III
    • 1007. Minimum Domino Rotations For Equal Row
    • 1031. Maximum Sum of Two Non-Overlapping Subarrays
    • 1099. Two Sum Less Than K
    • 1137. N-th Tribonacci Number
    • 1152. Analyze User Website Visit Pattern
    • 1229. Meeting Scheduler
    • 1234. Replace the Substring for Balanced String
    • 1248. Count Number of Nice Subarrays
  • Binary Search
    • 4. Median of Two Sorted Arrays
    • 33. Search in Rotated Sorted Array
    • 34. Find First and Last Position of Element in Sorted Array
    • 35. Search Insert Position
    • 69. Sqrt(x)
    • 74. Search a 2D Matrix
    • 81. Search in Rotated Sorted Array II
    • 153. Find Minimum in Rotated Sorted Array
    • 154. Find Minimum in Rotated Sorted Array II
    • 162. Find Peak Element
    • 240. Search a 2D Matrix II
    • 278. First Bad Version
    • 315. Count of Smaller Numbers After Self
    • 349. Intersection of Two Arrays
    • 350. Intersection of Two Arrays II
    • 374. Guess Number Higher or Lower
    • 378. Kth Smallest Element in a Sorted Matrix
    • 392. Is Subsequence
    • 410. Split Array Largest Sum
    • 658. Find K Closest Elements
    • 668. Kth Smallest Number in Multiplication Table
    • 719. Find K-th Smallest Pair Distance
    • 774. Minimize Max Distance to Gas Station
    • 786. K-th Smallest Prime Fraction
    • 875. Koko Eating Bananas
    • 1011. Capacity To Ship Packages Within D Days
    • 1095. Find in Mountain Array
    • 1231. Divide Chocolate
  • Stack
    • 20. Valid Parentheses
    • 71. Simplify Path
    • 84. Largest Rectangle in Histogram
    • 150. Evaluate Reverse Polish Notation
    • 224. Basic Calculator
    • 227. Basic Calculator II
    • 456. 132 Pattern
    • 496. Next Greater Element I
    • 503. Next Greater Element II
    • 636. Exclusive Time of Functions
    • 726. Number of Atoms
    • 735. Asteroid Collision
    • 1130. Minimum Cost Tree From Leaf Values
    • 1190. Reverse Substrings Between Each Pair of Parentheses
  • Heap
    • 215. Kth Largest Element in an Array
    • 218. The Skyline Problem
    • 295. Find Median from Data Stream
    • 347. Top K Frequent Elements
    • 373. Find K Pairs with Smallest Sums
    • 407. Trapping Rain Water II
    • 692. Top K Frequent Words
    • 703. Kth Largest Element in a Stream
    • 973. K Closest Points to Origin
    • 1046. Last Stone Weight
  • Bit Manipulation
    • 136. Single Number
    • 137. Single Number II
    • 187. Repeated DNA Sequences
    • 190. Reverse Bits
    • 191. Number of 1 Bits
    • 201. Bitwise AND of Numbers Range
    • 260. Single Number III
    • 318. Maximum Product of Word Lengths
    • 342. Power of Four
    • 371. Sum of Two Integers
    • 389. Find the Difference
    • 393. UTF-8 Validation
    • 405. Convert a Number to Hexadecimal
    • 411. Minimum Unique Word Abbreviation
    • 421. Maximum XOR of Two Numbers in an Array
    • 461. Hamming Distance
    • 477. Total Hamming Distance
  • Greedy
    • 45. Jump Game II
    • 55. Jump Game
    • 134. Gas Station
    • 135. Candy
    • 316. Remove Duplicate Letters
    • 321. Create Maximum Number
    • 358. Rearrange String k Distance Apart
    • 402. Remove K Digits
    • 435. Non-overlapping Intervals
    • 452. Minimum Number of Arrows to Burst Balloons
    • 621. Task Scheduler
    • 630. Course Schedule III
    • 646. Maximum Length of Pair Chain
    • 659. Split Array into Consecutive Subsequences
    • 738. Monotone Increasing Digits
    • 759. Employee Free Time
    • 767. Reorganize String
    • 846. Hand of Straights
    • 861. Score After Flipping Matrix
    • 991. Broken Calculator
    • 1055. Shortest Way to Form String
    • 1057. Campus Bikes
    • 1094. Car Pooling
    • 1167. Minimum Cost to Connect Sticks
    • 1296. Divide Array in Sets of K Consecutive Numbers
  • String
    • 3. Longest Substring Without Repeating Characters
    • 6. ZigZag Conversion
    • 12. Integer to Roman
    • 13. Roman to Integer
    • 14. Longest Common Prefix
    • 20. Valid Parentheses
    • 28. Implement strStr()
    • 30. Substring with Concatenation of All Words
    • 38. Count and Say
    • 43. Multiply Strings
    • 49. Group Anagrams
    • 53. Maximum Subarray
    • 66. Plus One
    • 67. Add Binary
    • 68. Text Justification
    • 76. Minimum Window Substring
    • 87. Scramble String
    • 125. Valid Palindrome
    • 151. Reverse Words in a String
    • 157. Read N Characters Given Read4
    • 159. Longest Substring with At Most Two Distinct Characters
    • 161. One Edit Distance
    • 165. Compare Version Numbers
    • 179. Largest Number
    • 186. Reverse Words in a String II
    • 214. Shortest Palindrome
    • 242. Valid Anagram
    • 249. Group Shifted Strings
    • 266. Palindrome Permutation
    • 271. Encode and Decode Strings
    • 273. Integer to English Words
    • 288. Unique Word Abbreviation
    • 290. Word Pattern
    • 291. Word Pattern II
    • 293. Flip Game
    • 336. Palindrome Pairs
    • 340. Longest Substring with At Most K Distinct Characters
    • 344. Reverse String
    • 345. Reverse Vowels of a String
    • 383. Ransom Note
    • 387. First Unique Character in a String
    • 392. Is Subsequence
    • 395. Longest Substring with At Least K Repeating Characters
    • 409. Longest Palindrome
    • 415. Add Strings
    • 424. Longest Repeating Character Replacement
    • 438. Find All Anagrams in a String
    • 443. String Compression
    • 451. Sort Characters By Frequency
    • 459. Repeated Substring Pattern
    • 482. License Key Formatting
    • 539. Minimum Time Difference
    • 541. Reverse String II
    • 551. Student Attendance Record I
    • 556. Next Greater Element III
    • 557. Reverse Words in a String III
    • 567. Permutation in String
    • 609. Find Duplicate File in System
    • 648. Replace Words
    • 657. Robot Return to Origin
    • 686. Repeated String Match
    • 696. Count Binary Substrings
    • 722. Remove Comments
    • 734. Sentence Similarity
    • 745. Prefix and Suffix Search
    • 771. Jewels and Stones
    • 777. Swap Adjacent in LR String
    • 792. Number of Matching Subsequences
    • 796. Rotate String
    • 809. Expressive Words
    • 811. Subdomain Visit Count
    • 819. Most Common Word
    • 843. Guess the Word
    • 844. Backspace String Compare
    • 917. Reverse Only Letters
    • 929. Unique Email Addresses
    • 937. Reorder Log Files
    • 953. Verifying an Alien Dictionary
    • 1003. Check If Word Is Valid After Substitutions
    • 1096. Brace Expansion II
    • 1108. Defanging an IP Address
    • 1119. Remove Vowels from a String
    • 1170. Compare Strings by Frequency of the Smallest Character
    • 1189. Maximum Number of Balloons
    • 1268. Search Suggestions System
  • Dynamic Programming
    • 5. Longest Palindromic Substring
    • 10. Regular Expression Matching
    • 32. Longest Valid Parentheses
    • 44. Wildcard Matching
    • 53. Maximum Subarray
    • 62. Unique Paths
    • 63. Unique Paths II
    • 64. Minimum Path Sum
    • 70. Climbing Stairs
    • 72. Edit Distance
    • 85. Maximal Rectangle
    • 91. Decode Ways
    • 96. Unique Binary Search Trees
    • 97. Interleaving String
    • 115. Distinct Subsequences
    • 120. Triangle
    • 139. Word Break
    • 152. Maximum Product Subarray
    • 174. Dungeon Game
    • 198. House Robber
    • 213. House Robber II
    • 221. Maximal Square
    • 276. Paint Fence
    • 279. Perfect Squares
    • 300. Longest Increasing Subsequence
    • 303. Range Sum Query - Immutable
    • 304. Range Sum Query 2D - Immutable
    • 312. Burst Balloons
    • 322. Coin Change
    • 338. Counting Bits
    • 343. Integer Break
    • 354. Russian Doll Envelopes
    • 357. Count Numbers with Unique Digits
    • 361. Bomb Enemy
    • 375. Guess Number Higher or Lower II
    • 377. Combination Sum IV
    • 413. Arithmetic Slices
    • 416. Partition Equal Subset Sum
    • 446. Arithmetic Slices II - Subsequence
    • 465. Optimal Account Balancing
    • 471. Encode String with Shortest Length
    • 472. Concatenated Words
    • 486. Predict the Winner
    • 494. Target Sum
    • 516. Longest Palindromic Subsequence
    • 518. Coin Change 2
    • 546. Remove Boxes
    • 552. Student Attendance Record II
    • 568. Maximum Vacation Days
    • 576. Out of Boundary Paths
    • 583. Delete Operation for Two Strings
    • 638. Shopping Offers
    • 639. Decode Ways II
    • 647. Palindromic Substrings
    • 673. Number of Longest Increasing Subsequence
    • 674. Longest Continuous Increasing Subsequence
    • 688. Knight Probability in Chessboard
    • 689. Maximum Sum of 3 Non-Overlapping Subarrays
    • 712. Minimum ASCII Delete Sum for Two Strings
    • 718. Maximum Length of Repeated Subarray
    • 727. Minimum Window Subsequence
    • 730. Count Different Palindromic Subsequences
    • 741. Cherry Pickup
    • 746. Min Cost Climbing Stairs
    • 764. Largest Plus Sign
    • 801. Minimum Swaps To Make Sequences Increasing
    • 818. Race Car
    • 837. New 21 Game
    • 877. Stone Game
    • 887. Super Egg Drop
    • 920. Number of Music Playlists
    • 931. Minimum Falling Path Sum
    • 935. Knight Dialer
    • 978. Longest Turbulent Subarray
    • 983. Minimum Cost For Tickets
    • 1000. Minimum Cost to Merge Stones
    • 1035. Uncrossed Lines
    • 1039. Minimum Score Triangulation of Polygon
    • 1043. Partition Array for Maximum Sum
    • 1048. Longest String Chain
    • 1066. Campus Bikes II
    • 1092. Shortest Common Supersequence
    • 1143. Longest Common Subsequence
  • Tree
    • 94. Binary Tree Inorder Traversal
    • 98. Validate Binary Search Tree
    • 99. Recover Binary Search Tree
    • 100. Same Tree
    • 101. Symmetric Tree
    • 102. Binary Tree Level Order Traversal
    • 103. Binary Tree Zigzag Level Order Traversal
    • 104. Maximum Depth of Binary Tree
    • 105. Construct Binary Tree from Preorder and Inorder Traversal
    • 106. Construct Binary Tree from Inorder and Postorder Traversal
    • 107. Binary Tree Level Order Traversal II
    • 108. Convert Sorted Array to Binary Search Tree
    • 110. Balanced Binary Tree
    • 111. Minimum Depth of Binary Tree
    • 112. Path Sum
    • 113. Path Sum II
    • 114. Flatten Binary Tree to Linked List
    • 116. Populating Next Right Pointers in Each Node
    • 117. Populating Next Right Pointers in Each Node II
    • 124. Binary Tree Maximum Path Sum
    • 129. Sum Root to Leaf Numbers
    • 144. Binary Tree Preorder Traversal
    • 145. Binary Tree Postorder Traversal
    • 156. Binary Tree Upside Down
    • 199. Binary Tree Right Side View
    • 222. Count Complete Tree Nodes
    • 226. Invert Binary Tree
    • 230. Kth Smallest Element in a BST
    • 235. Lowest Common Ancestor of a Binary Search Tree
    • 236. Lowest Common Ancestor of a Binary Tree
    • 250. Count Univalue Subtrees
    • 255. Verify Preorder Sequence in Binary Search Tree
    • 257. Binary Tree Paths
    • 270. Closest Binary Search Tree Value
    • 272. Closest Binary Search Tree Value II
    • 285. Inorder Successor in BST
    • 297. Serialize and Deserialize Binary Tree
    • 298. Binary Tree Longest Consecutive Sequence
    • 314. Binary Tree Vertical Order Traversal
    • 331. Verify Preorder Serialization of a Binary Tree
    • 333. Largest BST Subtree
    • 337. House Robber III
    • 426. Convert Binary Search Tree to Sorted Doubly Linked List
    • 427. Construct Quad Tree
    • 428. Serialize and Deserialize N-ary Tree
    • 429. N-ary Tree Level Order Traversal
    • 430. Flatten a Multilevel Doubly Linked List
    • 437. Path Sum III
    • 449. Serialize and Deserialize BST
    • 450. Delete Node in a BST
    • 501. Find Mode in Binary Search Tree
    • 508. Most Frequent Subtree Sum
    • 510. Inorder Successor in BST II
    • 513. Find Bottom Left Tree Value
    • 543. Diameter of Binary Tree
    • 545. Boundary of Binary Tree
    • 549. Binary Tree Longest Consecutive Sequence II
    • 559. Maximum Depth of N-ary Tree
    • 572. Subtree of Another Tree
    • 606. Construct String from Binary Tree
    • 617. Merge Two Binary Trees
    • 637. Average of Levels in Binary Tree
    • 652. Find Duplicate Subtrees
    • 653. Two Sum IV - Input is a BST
    • 654. Maximum Binary Tree
    • 655. Print Binary Tree
    • 666. Path Sum IV
    • 669. Trim a Binary Search Tree
    • 687. Longest Univalue Path
    • 700. Search in a Binary Search Tree
    • 701. Insert into a Binary Search Tree
    • 783. Minimum Distance Between BST Nodes
    • 834. Sum of Distances in Tree
    • 852. Peak Index in a Mountain Array
    • 863. All Nodes Distance K in Binary Tree
    • 889. Construct Binary Tree from Preorder and Postorder Traversal
    • 894. All Possible Full Binary Trees
    • 951. Flip Equivalent Binary Trees
    • 958. Check Completeness of a Binary Tree
    • 968. Binary Tree Cameras
    • 979. Distribute Coins in Binary Tree
    • 987. Vertical Order Traversal of a Binary Tree
    • 988. Smallest String Starting From Leaf
    • 993. Cousins in Binary Tree
    • 998. Maximum Binary Tree II
    • 1008. Construct Binary Search Tree from Preorder Traversal
    • 1038. Binary Search Tree to Greater Sum Tree
    • 1110. Delete Nodes And Return Forest
    • 1145. Binary Tree Coloring Game
    • 1214. Two Sum BSTs
  • Linked List
    • 2. Add Two Numbers
    • 19. Remove Nth Node From End of List
    • 21. Merge Two Sorted Lists
    • 23. Merge k Sorted Lists
    • 24. Swap Nodes in Pairs
    • 25. Reverse Nodes in k-Group
    • 61. Rotate List
    • 82. Remove Duplicates from Sorted List II
    • 83. Remove Duplicates from Sorted List
    • 92. Reverse Linked List II
    • 109. Convert Sorted List to Binary Search Tree
    • 133. Clone Graph
    • 138. Copy List with Random Pointer
    • 141. Linked List Cycle
    • 142. Linked List Cycle II
    • 143. Reorder List
    • 147. Insertion Sort List
    • 148. Sort List
    • 160. Intersection of Two Linked Lists
    • 203. Remove Linked List Elements
    • 206. Reverse Linked List
    • 234. Palindrome Linked List
    • 237. Delete Node in a Linked List
    • 328. Odd Even Linked List
    • 369. Plus One Linked List
    • 445. Add Two Numbers II
    • 708. Insert into a Cyclic Sorted List
    • 725. Split Linked List in Parts
  • Graph
    • 207. Course Schedule
    • 210. Course Schedule II
    • 261. Graph Valid Tree
    • 269. Alien Dictionary
    • 305. Number of Islands II
    • 310. Minimum Height Trees
    • 323. Number of Connected Components in an Undirected Graph
    • 332. Reconstruct Itinerary
    • 444. Sequence Reconstruction
    • 547. Friend Circles
    • 684. Redundant Connection
    • 685. Redundant Connection II
    • 721. Accounts Merge
    • 737. Sentence Similarity II
    • 743. Network Delay Time
    • 765. Couples Holding Hands
    • 778. Swim in Rising Water
    • 787. Cheapest Flights Within K Stops
    • 839. Similar String Groups
    • 924. Minimize Malware Spread
    • 947. Most Stones Removed with Same Row or Column
    • 959. Regions Cut By Slashes
    • 1101. The Earliest Moment When Everyone Become Friends
    • 1102. Path With Maximum Minimum Value
    • 1135. Connecting Cities With Minimum Cost
    • 1153. String Transforms Into Another String
  • Backtracking
    • 17. Letter Combinations of a Phone Number
    • 26. Generate Parentheses
    • 37. Sudoku Solver
    • 39. Combination Sum
    • 40. Combination Sum II
    • 46. Permutations
    • 47. Permutations II
    • 77. Combinations
    • 93. Restore IP Addresses
    • 140. Word Break II
    • 216. Combination Sum III
    • 241. Different Ways to Add Parentheses
    • 248. Strobogrammatic Number III
    • 254. Factor Combinations
    • 267. Palindrome Permutation II
    • 282. Expression Add Operators
    • 294. Flip Game II
    • 320. Generalized Abbreviation
    • 351. Android Unlock Patterns
    • 491. Increasing Subsequences
    • 679. 24 Game
    • 698. Partition to K Equal Sum Subsets
    • 756. Pyramid Transition Matrix
    • 784. Letter Case Permutation
    • 980. Unique Paths III
    • 1087. Brace Expansion
    • 1219. Path with Maximum Gold
    • 1258. Synonymous Sentences
  • Depth-First-Search & Breadth-First-Search
    • 51. N-Queens
    • 52. N-Queens II
    • 79. Word Search
    • 95. Unique Binary Search Trees II
    • 126. Word Ladder II
    • 127. Word Ladder
    • 130. Surrounded Regions
    • 212. Word Search II
    • 286. Walls and Gates
    • 301. Remove Invalid Parentheses
    • 317. Shortest Distance from All Buildings
    • 329. Longest Increasing Path in a Matrix
    • 339. Nested List Weight Sum
    • 364. Nested List Weight Sum II
    • 385. Mini Parser
    • 394. Decode String
    • 417. Pacific Atlantic Water Flow
    • 433. Minimum Genetic Mutation
    • 439. Ternary Expression Parser
    • 464. Can I Win
    • 489. Robot Room Cleaner
    • 490. The Maze
    • 499. The Maze III
    • 505. The Maze II
    • 529. Minesweeper
    • 542. 01 Matrix
    • 690. Employee Importance
    • 694. Number of Distinct Islands
    • 711. Number of Distinct Islands II
    • 733. Flood Fill
    • 752. Open the Lock
    • 753. Cracking the Safe
    • 772. Basic Calculator III
    • 773. Sliding Puzzle
    • 854. K-Similar Strings
    • 994. Rotting Oranges
    • 1034. Coloring A Border
    • 1162. As Far from Land as Possible
    • 1192. Critical Connections in a Network
    • 1197. Minimum Knight Moves
    • 1236. Web Crawler
    • 1306. Jump Game III
  • Math
    • 7. Reverse Integer
    • 8. String to Integer (atoi)
    • 9. Palindrome Number
    • 29. Divide Two Integers
    • 60. Permutation Sequence
    • 65. Valid Number
    • 89. Gray Code
    • 149. Max Points on a Line
    • 166. Fraction to Recurring Decimal
    • 168. Excel Sheet Column Title
    • 171. Excel Sheet Column Number
    • 172. Factorial Trailing Zeroes
    • 202. Happy Number
    • 204. Count Primes
    • 246. Strobogrammatic Number
    • 247. Strobogrammatic Number II
    • 263. Ugly Number
    • 264. Ugly Number II
    • 292. Nim Game
    • 296. Best Meeting Point
    • 313. Super Ugly Number
    • 319. Bulb Switcher
    • 365. Water and Jug Problem
    • 469. Convex Polygon
    • 780. Reaching Points
    • 794. Valid Tic-Tac-Toe State
    • 836. Rectangle Overlap
    • 942. DI String Match
    • 1017. Convert to Base -2
    • 1025. Divisor Game
    • 1056. Confusing Number
    • 1088. Confusing Number II
    • 1227. Airplane Seat Assignment Probability
    • 1232. Check If It Is a Straight Line
    • 1238. Circular Permutation in Binary Representation
    • 1250. Check If It Is a Good Array
  • Design
    • 146. LRU Cache
    • 155. Min Stack
    • 170. Two Sum III - Data structure design
    • 173. Binary Search Tree Iterator
    • 208. Implement Trie (Prefix Tree)
    • 211. Add and Search Word - Data structure design
    • 225. Implement Stack using Queues
    • 232. Implement Queue using Stacks
    • 251. Flatten 2D Vector
    • 281. Zigzag Iterator
    • 284. Peeking Iterator
    • 328. Random Pick Index
    • 341. Flatten Nested List Iterator
    • 346. Moving Average from Data Stream
    • 348. Design Tic-Tac-Toe
    • 352. Data Stream as Disjoint Intervals
    • 359. Logger Rate Limiter
    • 362. Design Hit Counter
    • 380. Insert Delete GetRandom O(1)
    • 381. Insert Delete GetRandom O(1) - Duplicates allowed
    • 384. Shuffle an Array
    • 398. Random Pick Index
    • 432. All O`one Data Structure
    • 460. LFU Cache
    • 528. Random Pick with Weight
    • 535. Encode and Decode TinyURL
    • 588. Design In-Memory File System
    • 604. Design Compressed String Iterator
    • 622. Design Circular Queue
    • 635. Design Log Storage System
    • 642. Design Search Autocomplete System
    • 705. Design HashSet
    • 706. Design HashMap
    • 707. Design Linked List
    • 716. Max Stack
    • 981. Time Based Key-Value Store
    • 1032. Stream of Characters
    • 1146. Snapshot Array
  • Old Interview Questions
    • Longest Word Chain
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