_LeetCode

1. Strings / Arrays & Hashing

• 1. Two Sum
• 6. Zigzag Conversion
• 14. Longest Common Prefix
• 28. Find the Index of the First Occurrence in a String
• 31. Next Permutation
• 36. Valid Sudoku
• 38. Count and Say
• 41. First Missing Positive
• 48. Rotate Image
• 49. Group Anagrams
• 54. Spiral Matrix
• 58. Length of Last Word
• 59. Spiral Matrix II
• 65. Valid Number
• 66. Plus One
• 73. Set Matrix Zeroes
• 118. Pascal’s Triangle
• 119. Pascal’s Triangle II
• 128. Longest Consecutive Sequence
• 151. Reverse Words in a String
• 157. Read N Characters Given Read4 🔒
• 158. Read N Characters Given Read4 II - Call Multiple Times 🔒
• 161. One Edit Distance 🔒
• 164. Maximum Gap
• 165. Compare Version Numbers
• 169. Majority Element
• 170. Two Sum III - Data structure design 🔒
• 186. Reverse Words in a String II 🔒
• 189. Rotate Array
• 205. Isomorphic Strings
• 214. Shortest Palindrome
• 217. Contains Duplicate
• 219. Contains Duplicate II
• 229. Majority Element II
• 238. Product of Array Except Self
• 242. Valid Anagram
• 243. Shortest Word Distance 🔒
• 244. Shortest Word Distance II 🔒
• 245. Shortest Word Distance III 🔒
• 249. Group Shifted Strings 🔒
• 251. Flatten 2D Vector 🔒
• 266. Palindrome Permutation 🔒
• 271. Encode and Decode Strings 🔒
• 274. H-Index
• 281. Zigzag Iterator 🔒
• 284. Peeking Iterator
• 288. Unique Word Abbreviation 🔒
• 289. Game of Life
• 290. Word Pattern
• 293. Flip Game 🔒
• 299. Bulls and Cows
• 311. Sparse Matrix Multiplication 🔒
• 325. Maximum Size Subarray Sum Equals k 🔒
• 348. Design Tic-Tac-Toe 🔒
• 349. Intersection of Two Arrays
• 350. Intersection of Two Arrays II
• 353. Design Snake Game 🔒
• 359. Logger Rate Limiter 🔒
• 370. Range Addition 🔒
• 379. Design Phone Directory 🔒
• 383. Ransom Note
• 384. Shuffle an Array
• 387. First Unique Character in a String
• 398. Random Pick Index
• 408. Valid Word Abbreviation 🔒
• 412. Fizz Buzz
• 414. Third Maximum Number
• 415. Add Strings
• 418. Sentence Screen Fitting 🔒
• 419. Battleships in a Board
• 422. Valid Word Square 🔒
• 434. Number of Segments in a String
• 442. Find All Duplicates in an Array
• 443. String Compression
• 447. Number of Boomerangs
• 448. Find All Numbers Disappeared in an Array
• 454. 4Sum II
• 459. Repeated Substring Pattern
• 463. Island Perimeter
• 468. Validate IP Address
• 481. Magical String
• 482. License Key Formatting
• 485. Max Consecutive Ones
• 492. Construct the Rectangle
• 495. Teemo Attacking
• 498. Diagonal Traverse
• 500. Keyboard Row

2. Two Pointers

• 11. Container With Most Water
• 15. 3Sum
• 16. 3Sum Closest
• 18. 4Sum
• 26. Remove Duplicates from Sorted Array
• 27. Remove Element
• 42. Trapping Rain Water
• 75. Sort Colors
• 80. Remove Duplicates from Sorted Array II
• 88. Merge Sorted Array
• 125. Valid Palindrome
• 167. Two Sum II - Input Array Is Sorted
• 259. 3Sum Smaller 🔒
• 283. Move Zeroes
• 287. Find the Duplicate Number
• 344. Reverse String
• 345. Reverse Vowels of a String
• 360. Sort Transformed Array 🔒
• 392. Is Subsequence
• 457. Circular Array Loop
• 462. Minimum Moves to Equal Array Elements II

3. Sliding Window

• 3. Longest Substring Without Repeating Characters
• 30. Substring with Concatenation of All Words
• 76. Minimum Window Substring
• 159. Longest Substring with At Most Two Distinct Characters 🔒
• 187. Repeated DNA Sequences
• 209. Minimum Size Subarray Sum
• 220. Contains Duplicate III
• 239. Sliding Window Maximum
• 340. Longest Substring with At Most K Distinct Characters 🔒
• 346. Moving Average from Data Stream 🔒
• 362. Design Hit Counter 🔒
• 395. Longest Substring with At Least K Repeating Characters
• 424. Longest Repeating Character Replacement
• 438. Find All Anagrams in a String
• 480. Sliding Window Median
• 487. Max Consecutive Ones II 🔒

4. Stack

• 20. Valid Parentheses
• 71. Simplify Path
• 85. Maximal Rectangle
• 84. Largest Rectangle in Histogram
• 150. Evaluate Reverse Polish Notation
• 155. Min Stack
• 224. Basic Calculator
• 225. Implement Stack using Queues
• 227. Basic Calculator II
• 232. Implement Queue using Stacks
• 316. Remove Duplicate Letters
• 341. Flatten Nested List Iterator
• 385. Mini Parser
• 388. Longest Absolute File Path
• 394. Decode String
• 402. Remove K Digits
• 456. 132 Pattern
• 439. Ternary Expression Parser 🔒
• 496. Next Greater Element I

5. 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
• 275. H-Index II
• 278. First Bad Version
• 302. Smallest Rectangle Enclosing Black Pixels 🔒
• 367. Valid Perfect Square
• 374. Guess Number Higher or Lower
• 410. Split Array Largest Sum
• 436. Find Right Interval
• 441. Arranging Coins
• 475. Heaters
• 483. Smallest Good Base

6. Linked List

• 2. Add Two Numbers
• 19. Remove Nth Node From End of List
• 21. Merge Two 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
• 86. Partition List
• 92. Reverse Linked List II
• 138. Copy List with Random Pointer
• 141. Linked List Cycle
• 142. Linked List Cycle II
• 143. Reorder List
• 146. LRU Cache
• 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 🔒
• 382. Linked List Random Node
• 430. Flatten a Multilevel Doubly Linked List
• 445. Add Two Numbers II
• 460. LFU Cache

7. Trees

• 94. Binary Tree Inorder Traversal
• 95. Unique Binary Search Trees II
• 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
• 109. Convert Sorted List to Binary Search Tree
• 110. Balanced Binary Tree
• 111. Minimum Depth of Binary Tree
• 112. Path Sum
• 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 🔒
• 173. Binary Search Tree Iterator
• 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 🔒
• 307. Range Sum Query - Mutable
• 314. Binary Tree Vertical Order Traversal 🔒
• 331. Verify Preorder Serialization of a Binary Tree
• 333. Largest BST Subtree 🔒
• 337. House Robber III
• 366. Find Leaves of Binary Tree 🔒
• 404. Sum of Left Leaves
• 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
• 431. Encode N-ary Tree to Binary Tree 🔒
• 437. Path Sum III
• 449. Serialize and Deserialize BST
• 450. Delete Node in a BST
• 493. Reverse Pairs

8. Heap / Priority Queue

• 23. Merge k Sorted Lists
• 215. Kth Largest Element in an Array
• 218. The Skyline Problem
• 264. Ugly Number II
• 295. Find Median from Data Stream
• 313. Super Ugly Number
• 315. Count of Smaller Numbers After Self
• 327. Count of Range Sum
• 347. Top K Frequent Elements
• 355. Design Twitter
• 358. Rearrange String k Distance Apart 🔒
• 373. Find K Pairs with Smallest Sums
• 378. Kth Smallest Element in a Sorted Matrix
• 407. Trapping Rain Water II
• 432. All One Data Structure
• 451. Sort Characters By Frequency

9. Backtracking

• 17. Letter Combinations of a Phone Number
• 22. Generate Parentheses
• 37. Sudoku Solver
• 39. Combination Sum
• 40. Combination Sum II
• 46. Permutations
• 47. Permutations II
• 51. N-Queens
• 52. N-Queens II
• 60. Permutation Sequence
• 77. Combinations
• 78. Subsets
• 79. Word Search
• 90. Subsets II
• 93. Restore IP Addresses
• 113. Path Sum II
• 131. Palindrome Partitioning
• 216. Combination Sum III
• 241. Different Ways to Add Parentheses
• 247. Strobogrammatic Number II 🔒
• 248. Strobogrammatic Number III 🔒
• 254. Factor Combinations 🔒
• 267. Palindrome Permutation II 🔒
• 282. Expression Add Operators
• 291. Word Pattern II 🔒
• 294. Flip Game II 🔒
• 301. Remove Invalid Parentheses
• 306. Additive Number
• 320. Generalized Abbreviation 🔒
• 351. Android Unlock Patterns 🔒
• 411. Minimum Unique Word Abbreviation 🔒
• 465. Optimal Account Balancing 🔒
• 473. Matchsticks to Square
• 488. Zuma Game
• 489. Robot Room Cleaner 🔒
• 491. Non-decreasing Subsequences

10. Tries

• 208. Implement Trie (Prefix Tree)
• 211. Design Add and Search Words Data Structure
• 212. Word Search II
• 336. Palindrome Pairs
• 386. Lexicographical Numbers
• 421. Maximum XOR of Two Numbers in an Array
• 425. Word Squares 🔒
• 440. K-th Smallest in Lexicographical Order
• 467. Unique Substrings in Wraparound String
• 472. Concatenated Words

11. Graphs

• 126. Word Ladder II
• 127. Word Ladder
• 130. Surrounded Regions
• 133. Clone Graph
• 200. Number of Islands
• 207. Course Schedule
• 210. Course Schedule II
• 261. Graph Valid Tree 🔒
• 277. Find the Celebrity 🔒
• 286. Walls and Gates 🔒
• 305. Number of Islands II 🔒
• 310. Minimum Height Trees
• 317. Shortest Distance from All Buildings 🔒
• 323. Number of Connected Components in an Undirected Graph 🔒
• 329. Longest Increasing Path in a Matrix
• 339. Nested List Weight Sum 🔒
• 364. Nested List Weight Sum II 🔒
• 399. Evaluate Division
• 417. Pacific Atlantic Water Flow
• 433. Minimum Genetic Mutation
• 444. Sequence Reconstruction 🔒
• 490. The Maze 🔒

12. Advanced Graphs

• 269. Alien Dictionary 🔒
• 332. Reconstruct Itinerary
• 499. The Maze III 🔒

13. 1D Dynamic Programming

• 53. Maximum Subarray
• 70. Climbing Stairs
• 91. Decode Ways
• 96. Unique Binary Search Trees
• 123. Best Time to Buy and Sell Stock III
• 139. Word Break
• 140. Word Break II
• 152. Maximum Product Subarray
• 188. Best Time to Buy and Sell Stock IV
• 198. House Robber
• 213. House Robber II
• 256. Paint House 🔒
• 265. Paint House II 🔒
• 276. Paint Fence 🔒
• 279. Perfect Squares
• 300. Longest Increasing Subsequence
• 303. Range Sum Query - Immutable
• 309. Best Time to Buy and Sell Stock with Cooldown
• 322. Coin Change
• 343. Integer Break
• 368. Largest Divisible Subset
• 375. Guess Number Higher or Lower II
• 376. Wiggle Subsequence
• 377. Combination Sum IV
• 403. Frog Jump
• 413. Arithmetic Slices
• 416. Partition Equal Subset Sum
• 446. Arithmetic Slices II - Subsequence
• 464. Can I Win
• 474. Ones and Zeroes
• 486. Predict the Winner
• 494. Target Sum

14. 2D Dynamic Programming

• 5. Longest Palindromic Substring
• 10. Regular Expression Matching
• 32. Longest Valid Parentheses
• 44. Wildcard Matching
• 62. Unique Paths
• 63. Unique Paths II
• 64. Minimum Path Sum
• 72. Edit Distance
• 87. Scramble String
• 97. Interleaving String
• 115. Distinct Subsequences
• 120. Triangle
• 132. Palindrome Partitioning II
• 174. Dungeon Game
• 221. Maximal Square
• 304. Range Sum Query 2D - Immutable
• 308. Range Sum Query 2D - Mutable 🔒
• 312. Burst Balloons
• 354. Russian Doll Envelopes
• 361. Bomb Enemy 🔒
• 363. Max Sum of Rectangle No Larger Than K
• 471. Encode String with Shortest Length 🔒

15. Greedy

• 45. Jump Game II
• 55. Jump Game
• 68. Text Justification
• 121. Best Time to Buy and Sell Stock
• 122. Best Time to Buy and Sell Stock II
• 134. Gas Station
• 135. Candy
• 179. Largest Number
• 280. Wiggle Sort 🔒
• 321. Create Maximum Number
• 324. Wiggle Sort II
• 330. Patching Array
• 334. Increasing Triplet Subsequence
• 380. Insert Delete GetRandom O(1)
• 381. Insert Delete GetRandom O(1) - Duplicates allowed
• 406. Queue Reconstruction by Height
• 420. Strong Password Checker
• 455. Assign Cookies
• 484. Find Permutation 🔒

16. Intervals

• 56. Merge Intervals
• 57. Insert Interval
• 163. Missing Ranges 🔒
• 228. Summary Ranges
• 252. Meeting Rooms 🔒
• 253. Meeting Rooms II 🔒
• 352. Data Stream as Disjoint Intervals
• 391. Perfect Rectangle
• 435. Non-overlapping Intervals
• 452. Minimum Number of Arrows to Burst Balloons

17. Math & Geometry

• 7. Reverse Integer
• 8. String to Integer (atoi)
• 9. Palindrome Number
• 12. Integer to Roman
• 13. Roman to Integer
• 29. Divide Two Integers
• 43. Multiply Strings
• 50. Pow(x, n)
• 67. Add Binary
• 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
• 223. Rectangle Area
• 233. Number of Digit One
• 246. Strobogrammatic Number 🔒
• 258. Add Digits
• 263. Ugly Number
• 273. Integer to English Words
• 292. Nim Game
• 296. Best Meeting Point 🔒
• 319. Bulb Switcher
• 326. Power of Three
• 335. Self Crossing
• 356. Line Reflection 🔒
• 357. Count Numbers with Unique Digits
• 365. Water and Jug Problem
• 372. Super Pow
• 390. Elimination Game
• 396. Rotate Function
• 400. Nth Digit
• 405. Convert a Number to Hexadecimal
• 423. Reconstruct Original Digits from English
• 453. Minimum Moves to Equal Array Elements
• 458. Poor Pigs
• 469. Convex Polygon 🔒
• 470. Implement Rand10() Using Rand7()
• 478. Generate Random Point in a Circle
• 479. Largest Palindrome Product
• 497. Random Point in Non-overlapping Rectangles

18. Bit Manipulation

• 89. Gray Code
• 136. Single Number
• 137. Single Number II
• 190. Reverse Bits
• 191. Number of 1 Bits
• 201. Bitwise AND of Numbers Range
• 231. Power of Two
• 260. Single Number III
• 268. Missing Number
• 318. Maximum Product of Word Lengths
• 338. Counting Bits
• 342. Power of Four
• 371. Sum of Two Integers
• 389. Find the Difference
• 393. UTF-8 Validation
• 397. Integer Replacement
• 401. Binary Watch
• 461. Hamming Distance
• 476. Number Complement
• 477. Total Hamming Distance

19. SQL

• 175. Combine Two Tables
• 176. Second Highest Salary
• 177. Nth Highest Salary
• 178. Rank Scores
• 180. Consecutive Numbers
• 181. Employees Earning More Than Their Managers
• 182. Duplicate Emails
• 183. Customers Who Never Order
• 184. Department Highest Salary
• 185. Department Top Three Salaries
• 196. Delete Duplicate Emails
• 197. Rising Temperature
• 262. Trips and Users