Clean, optimized C++ solutions for LeetCode problems 1–700.
Each solution is in all_solutions.cpp, organized by problem number with complexity analysis.
| Number | Problem Name | Difficulty | Solution |
|---|---|---|---|
| 0001 | Two Sum | Easy | Code |
| 0002 | Add Two Numbers | Medium | Code |
| 0003 | Longest Substring Without Repeating Characters | Medium | Code |
| 0004 | Median of Two Sorted Arrays | Hard | Code |
| 0005 | Longest Palindromic Substring | Medium | Code |
| 0006 | Zigzag Conversion | Medium | Code |
| 0007 | Reverse Integer | Medium | Code |
| 0008 | String to Integer (atoi) | Medium | Code |
| 0009 | Palindrome Number | Easy | Code |
| 0010 | Regular Expression Matching | Hard | Code |
| 0011 | Container With Most Water | Medium | Code |
| 0012 | Integer to Roman | Medium | Code |
| 0013 | Roman to Integer | Easy | Code |
| 0014 | Longest Common Prefix | Easy | Code |
| 0015 | 3Sum | Medium | Code |
| 0016 | 3Sum Closest | Medium | Code |
| 0017 | Letter Combinations of a Phone Number | Medium | Code |
| 0018 | 4Sum | Medium | Code |
| 0019 | Remove Nth Node From End of List | Medium | Code |
| 0020 | Valid Parentheses | Easy | Code |
| 0021 | Merge Two Sorted Lists | Easy | Code |
| 0022 | Generate Parentheses | Medium | Code |
| 0023 | Merge k Sorted Lists | Hard | Code |
| 0024 | Swap Nodes in Pairs | Medium | Code |
| 0025 | Reverse Nodes in k-Group | Hard | Code |
| 0026 | Remove Duplicates from Sorted Array | Easy | Code |
| 0027 | Remove Element | Easy | Code |
| 0028 | Find the Index of the First Occurrence in a String | Easy | Code |
| 0029 | Divide Two Integers | Medium | Code |
| 0030 | Substring with Concatenation of All Words | Hard | Code |
| 0031 | Next Permutation | Medium | Code |
| 0032 | Longest Valid Parentheses | Hard | Code |
| 0033 | Search in Rotated Sorted Array | Medium | Code |
| 0034 | Find First and Last Position of Element in Sorted Array | Medium | Code |
| 0035 | Search Insert Position | Easy | Code |
| 0036 | Valid Sudoku | Medium | Code |
| 0037 | Sudoku Solver | Hard | Code |
| 0038 | Count and Say | Medium | Code |
| 0039 | Combination Sum | Medium | Code |
| 0040 | Combination Sum II | Medium | Code |
| 0041 | First Missing Positive | Hard | Code |
| 0042 | Trapping Rain Water | Hard | Code |
| 0043 | Multiply Strings | Medium | Code |
| 0044 | Wildcard Matching | Hard | Code |
| 0045 | Jump Game II | Medium | Code |
| 0046 | Permutations | Medium | Code |
| 0047 | Permutations II | Medium | Code |
| 0048 | Rotate Image | Medium | Code |
| 0049 | Group Anagrams | Medium | Code |
| 0050 | Pow(x, n) | Medium | Code |
| 0051 | N-Queens | Hard | Code |
| 0052 | N-Queens II | Hard | Code |
| 0053 | Maximum Subarray | Medium | Code |
| 0054 | Spiral Matrix | Medium | Code |
| 0055 | Jump Game | Medium | Code |
| 0056 | Merge Intervals | Medium | Code |
| 0057 | Insert Interval | Medium | Code |
| 0058 | Length of Last Word | Easy | Code |
| 0059 | Spiral Matrix II | Medium | Code |
| 0060 | Permutation Sequence | Hard | Code |
| 0061 | Rotate List | Medium | Code |
| 0062 | Unique Paths | Medium | Code |
| 0063 | Unique Paths II | Medium | Code |
| 0064 | Minimum Path Sum | Medium | Code |
| 0065 | Valid Number | Hard | Code |
| 0066 | Plus One | Easy | Code |
| 0067 | Add Binary | Easy | Code |
| 0068 | Text Justification | Hard | Code |
| 0069 | Sqrt(x) | Easy | Code |
| 0070 | Climbing Stairs | Easy | Code |
| 0071 | Simplify Path | Medium | Code |
| 0072 | Edit Distance | Medium | Code |
| 0073 | Set Matrix Zeroes | Medium | Code |
| 0074 | Search a 2D Matrix | Medium | Code |
| 0075 | Sort Colors | Medium | Code |
| 0076 | Minimum Window Substring | Hard | Code |
| 0077 | Combinations | Medium | Code |
| 0078 | Subsets | Medium | Code |
| 0079 | Word Search | Medium | Code |
| 0080 | Remove Duplicates from Sorted Array II | Medium | Code |
| 0081 | Search in Rotated Sorted Array II | Medium | Code |
| 0082 | Remove Duplicates from Sorted List II | Medium | Code |
| 0083 | Remove Duplicates from Sorted List | Easy | Code |
| 0084 | Largest Rectangle in Histogram | Hard | Code |
| 0085 | Maximal Rectangle | Hard | Code |
| 0086 | Partition List | Medium | Code |
| 0087 | Scramble String | Hard | Code |
| 0088 | Merge Sorted Array | Easy | Code |
| 0089 | Gray Code | Medium | Code |
| 0090 | Subsets II | Medium | Code |
| 0091 | Decode Ways | Medium | Code |
| 0092 | Reverse Linked List II | Medium | Code |
| 0093 | Restore IP Addresses | Medium | Code |
| 0094 | Binary Tree Inorder Traversal | Easy | Code |
| 0095 | Unique Binary Search Trees II | Medium | Code |
| 0096 | Unique Binary Search Trees | Medium | Code |
| 0097 | Interleaving String | Medium | Code |
| 0098 | Validate Binary Search Tree | Medium | Code |
| 0099 | Recover Binary Search Tree | Medium | Code |
| 0100 | Same Tree | Easy | Code |
| 0101 | Symmetric Tree | Easy | Code |
| 0102 | Binary Tree Level Order Traversal | Medium | Code |
| 0103 | Binary Tree Zigzag Level Order Traversal | Medium | Code |
| 0104 | Maximum Depth of Binary Tree | Easy | Code |
| 0105 | Construct Binary Tree from Preorder and Inorder Traversal | Medium | Code |
| 0106 | Construct Binary Tree from Inorder and Postorder Traversal | Medium | Code |
| 0107 | Binary Tree Level Order Traversal II | Medium | Code |
| 0108 | Convert Sorted Array to Binary Search Tree | Easy | Code |
| 0109 | Convert Sorted List to Binary Search Tree | Medium | Code |
| 0110 | Balanced Binary Tree | Easy | Code |
| 0111 | Minimum Depth of Binary Tree | Easy | Code |
| 0112 | Path Sum | Easy | Code |
| 0113 | Path Sum II | Medium | Code |
| 0114 | Flatten Binary Tree to Linked List | Medium | Code |
| 0115 | Distinct Subsequences | Hard | Code |
| 0116 | Populating Next Right Pointers in Each Node | Medium | Code |
| 0117 | Populating Next Right Pointers in Each Node II | Medium | Code |
| 0118 | Pascal's Triangle | Easy | Code |
| 0119 | Pascal's Triangle II | Easy | Code |
| 0120 | Triangle | Medium | Code |
| 0121 | Best Time to Buy and Sell Stock | Easy | Code |
| 0122 | Best Time to Buy and Sell Stock II | Medium | Code |
| 0123 | Best Time to Buy and Sell Stock III | Hard | Code |
| 0124 | Binary Tree Maximum Path Sum | Hard | Code |
| 0125 | Valid Palindrome | Easy | Code |
| 0126 | Word Ladder II | Hard | Code |
| 0127 | Word Ladder | Hard | Code |
| 0128 | Longest Consecutive Sequence | Medium | Code |
| 0129 | Sum Root to Leaf Numbers | Medium | Code |
| 0130 | Surrounded Regions | Medium | Code |
| 0131 | Palindrome Partitioning | Medium | Code |
| 0132 | Palindrome Partitioning II | Hard | Code |
| 0133 | Clone Graph | Medium | Code |
| 0134 | Gas Station | Medium | Code |
| 0135 | Candy | Hard | Code |
| 0136 | Single Number | Easy | Code |
| 0137 | Single Number II | Medium | Code |
| 0138 | Copy List with Random Pointer | Medium | Code |
| 0139 | Word Break | Medium | Code |
| 0140 | Word Break II | Hard | Code |
| 0141 | Linked List Cycle | Easy | Code |
| 0142 | Linked List Cycle II | Medium | Code |
| 0143 | Reorder List | Medium | Code |
| 0144 | Binary Tree Preorder Traversal | Easy | Code |
| 0145 | Binary Tree Postorder Traversal | Easy | Code |
| 0146 | LRU Cache | Medium | Code |
| 0147 | Insertion Sort List | Medium | Code |
| 0148 | Sort List | Medium | Code |
| 0149 | Max Points on a Line | Hard | Code |
| 0150 | Evaluate Reverse Polish Notation | Medium | Code |
| 0151 | Reverse Words in a String | Medium | Code |
| 0152 | Maximum Product Subarray | Medium | Code |
| 0153 | Find Minimum in Rotated Sorted Array | Medium | Code |
| 0154 | Find Minimum in Rotated Sorted Array II | Hard | Code |
| 0155 | Min Stack | Medium | Code |
| 0156 | Binary Tree Upside Down | Medium | Code |
| 0157 | Read N Characters Given Read4 | Easy | Code |
| 0158 | Read N Characters Given Read4 II | Hard | Code |
| 0159 | Longest Substring with At Most Two Distinct Characters | Medium | Code |
| 0160 | Intersection of Two Linked Lists | Easy | Code |
| 0161 | One Edit Distance | Medium | Code |
| 0162 | Find Peak Element | Medium | Code |
| 0163 | Missing Ranges | Easy | Code |
| 0164 | Maximum Gap | Hard | Code |
| 0165 | Compare Version Numbers | Medium | Code |
| 0166 | Fraction to Recurring Decimal | Medium | Code |
| 0167 | Two Sum II - Input Array Is Sorted | Medium | Code |
| 0168 | Excel Sheet Column Title | Easy | Code |
| 0169 | Majority Element | Easy | Code |
| 0170 | Two Sum III - Data Structure Design | Easy | Code |
| 0171 | Excel Sheet Column Number | Easy | Code |
| 0172 | Factorial Trailing Zeroes | Medium | Code |
| 0173 | Binary Search Tree Iterator | Medium | Code |
| 0174 | Dungeon Game | Hard | Code |
| 0175 | Combine Two Tables | Easy | Code |
| 0176 | Second Highest Salary | Medium | Code |
| 0177 | Nth Highest Salary | Medium | Code |
| 0178 | Rank Scores | Medium | Code |
| 0179 | Largest Number | Medium | Code |
| 0180 | Consecutive Numbers | Medium | Code |
| 0181 | Employees Earning More Than Their Managers | Easy | Code |
| 0182 | Duplicate Emails | Easy | Code |
| 0183 | Customers Who Never Order | Easy | Code |
| 0184 | Department Highest Salary | Medium | Code |
| 0185 | Department Top Three Salaries | Hard | Code |
| 0186 | Reverse Words in a String II | Medium | Code |
| 0187 | Repeated DNA Sequences | Medium | Code |
| 0188 | Best Time to Buy and Sell Stock IV | Hard | Code |
| 0189 | Rotate Array | Medium | Code |
| 0190 | Reverse Bits | Easy | Code |
| 0191 | Number of 1 Bits | Easy | Code |
| 0192 | Word Frequency | Medium | Code |
| 0193 | Valid Phone Numbers | Easy | Code |
| 0194 | Transpose File | Medium | Code |
| 0195 | Tenth Line | Easy | Code |
| 0196 | Delete Duplicate Emails | Easy | Code |
| 0197 | Rising Temperature | Easy | Code |
| 0198 | House Robber | Medium | Code |
| 0199 | Binary Tree Right Side View | Medium | Code |
| 0200 | Number of Islands | Medium | Code |
| 0201 | Bitwise AND of Numbers Range | Medium | Code |
| 0202 | Happy Number | Easy | Code |
| 0203 | Remove Linked List Elements | Easy | Code |
| 0204 | Count Primes | Medium | Code |
| 0205 | Isomorphic Strings | Easy | Code |
| 0206 | Reverse Linked List | Easy | Code |
| 0207 | Course Schedule | Medium | Code |
| 0208 | Implement Trie (Prefix Tree) | Medium | Code |
| 0209 | Minimum Size Subarray Sum | Medium | Code |
| 0210 | Course Schedule II | Medium | Code |
| 0211 | Design Add and Search Words Data Structure | Medium | Code |
| 0212 | Word Search II | Hard | Code |
| 0213 | House Robber II | Medium | Code |
| 0214 | Shortest Palindrome | Hard | Code |
| 0215 | Kth Largest Element in an Array | Medium | Code |
| 0216 | Combination Sum III | Medium | Code |
| 0217 | Contains Duplicate | Easy | Code |
| 0218 | The Skyline Problem | Hard | Code |
| 0219 | Contains Duplicate II | Easy | Code |
| 0220 | Contains Duplicate III | Hard | Code |
| 0221 | Maximal Square | Medium | Code |
| 0222 | Count Complete Tree Nodes | Easy | Code |
| 0223 | Rectangle Area | Medium | Code |
| 0224 | Basic Calculator | Hard | Code |
| 0225 | Implement Stack using Queues | Easy | Code |
| 0226 | Invert Binary Tree | Easy | Code |
| 0227 | Basic Calculator II | Medium | Code |
| 0228 | Summary Ranges | Easy | Code |
| 0229 | Majority Element II | Medium | Code |
| 0230 | Kth Smallest Element in a BST | Medium | Code |
| 0231 | Power of Two | Easy | Code |
| 0232 | Implement Queue using Stacks | Easy | Code |
| 0233 | Number of Digit One | Hard | Code |
| 0234 | Palindrome Linked List | Easy | Code |
| 0235 | Lowest Common Ancestor of a Binary Search Tree | Medium | Code |
| 0236 | Lowest Common Ancestor of a Binary Tree | Medium | Code |
| 0237 | Delete Node in a Linked List | Medium | Code |
| 0238 | Product of Array Except Self | Medium | Code |
| 0239 | Sliding Window Maximum | Hard | Code |
| 0240 | Search a 2D Matrix II | Medium | Code |
| 0241 | Different Ways to Add Parentheses | Medium | Code |
| 0242 | Valid Anagram | Easy | Code |
| 0243 | Shortest Word Distance | Easy | Code |
| 0244 | Shortest Word Distance II | Medium | Code |
| 0245 | Shortest Word Distance III | Medium | Code |
| 0246 | Strobogrammatic Number | Easy | Code |
| 0247 | Strobogrammatic Number II | Medium | Code |
| 0248 | Strobogrammatic Number III | Hard | Code |
| 0249 | Group Shifted Strings | Medium | Code |
| 0250 | Count Univalue Subtrees | Medium | Code |
| 0251 | Flatten 2D Vector | Medium | Code |
| 0252 | Meeting Rooms | Easy | Code |
| 0253 | Meeting Rooms II | Medium | Code |
| 0254 | Factor Combinations | Medium | Code |
| 0255 | Verify Preorder Sequence in Binary Search Tree | Medium | Code |
| 0256 | Paint House | Medium | Code |
| 0257 | Binary Tree Paths | Easy | Code |
| 0258 | Add Digits | Easy | Code |
| 0259 | 3Sum Smaller | Medium | Code |
| 0260 | Single Number III | Medium | Code |
| 0261 | Graph Valid Tree | Medium | Code |
| 0262 | Trips and Users | Hard | Code |
| 0263 | Ugly Number | Easy | Code |
| 0264 | Ugly Number II | Medium | Code |
| 0265 | Paint House II | Hard | Code |
| 0266 | Palindrome Permutation | Easy | Code |
| 0267 | Palindrome Permutation II | Medium | Code |
| 0268 | Missing Number | Easy | Code |
| 0269 | Alien Dictionary | Hard | Code |
| 0270 | Closest Binary Search Tree Value | Easy | Code |
| 0271 | Encode and Decode Strings | Medium | Code |
| 0272 | Closest Binary Search Tree Value II | Hard | Code |
| 0273 | Integer to English Words | Hard | Code |
| 0274 | H-Index | Medium | Code |
| 0275 | H-Index II | Medium | Code |
| 0276 | Paint Fence | Medium | Code |
| 0277 | Find the Celebrity | Medium | Code |
| 0278 | First Bad Version | Easy | Code |
| 0279 | Perfect Squares | Medium | Code |
| 0280 | Wiggle Sort | Medium | Code |
| 0281 | Zigzag Iterator | Medium | Code |
| 0282 | Expression Add Operators | Hard | Code |
| 0283 | Move Zeroes | Easy | Code |
| 0284 | Peeking Iterator | Medium | Code |
| 0285 | Inorder Successor in BST | Medium | Code |
| 0286 | Walls and Gates | Medium | Code |
| 0287 | Find the Duplicate Number | Medium | Code |
| 0288 | Unique Word Abbreviation | Medium | Code |
| 0289 | Game of Life | Medium | Code |
| 0290 | Word Pattern | Easy | Code |
| 0291 | Word Pattern II | Medium | Code |
| 0292 | Nim Game | Easy | Code |
| 0293 | Flip Game | Easy | Code |
| 0294 | Flip Game II | Medium | Code |
| 0295 | Find Median from Data Stream | Hard | Code |
| 0296 | Best Meeting Point | Hard | Code |
| 0297 | Serialize and Deserialize Binary Tree | Hard | Code |
| 0298 | Binary Tree Longest Consecutive Sequence | Medium | Code |
| 0299 | Bulls and Cows | Medium | Code |
| 0300 | Longest Increasing Subsequence | Medium | Code |
| 0301 | Remove Invalid Parentheses | Hard | Code |
| 0302 | Smallest Rectangle Enclosing Black Pixels | Hard | Code |
| 0303 | Range Sum Query - Immutable | Easy | Code |
| 0304 | Range Sum Query 2D - Immutable | Medium | Code |
| 0305 | Number of Islands II | Hard | Code |
| 0306 | Additive Number | Medium | Code |
| 0307 | Range Sum Query - Mutable | Medium | Code |
| 0308 | Range Sum Query 2D - Mutable | Hard | Code |
| 0309 | Best Time to Buy and Sell Stock with Cooldown | Medium | Code |
| 0310 | Minimum Height Trees | Medium | Code |
| 0311 | Sparse Matrix Multiplication | Medium | Code |
| 0312 | Burst Balloons | Hard | Code |
| 0313 | Super Ugly Number | Medium | Code |
| 0314 | Binary Tree Vertical Order Traversal | Medium | Code |
| 0315 | Count of Smaller Numbers After Self | Hard | Code |
| 0316 | Remove Duplicate Letters | Medium | Code |
| 0317 | Shortest Distance from All Buildings | Hard | Code |
| 0318 | Maximum Product of Word Lengths | Medium | Code |
| 0319 | Bulb Switcher | Medium | Code |
| 0320 | Generalized Abbreviation | Medium | Code |
| 0321 | Create Maximum Number | Hard | Code |
| 0322 | Coin Change | Medium | Code |
| 0323 | Number of Connected Components in an Undirected Graph | Medium | Code |
| 0324 | Wiggle Sort II | Medium | Code |
| 0325 | Maximum Size Subarray Sum Equals k | Medium | Code |
| 0326 | Power of Three | Easy | Code |
| 0327 | Count of Range Sum | Hard | Code |
| 0328 | Odd Even Linked List | Medium | Code |
| 0329 | Longest Increasing Path in a Matrix | Hard | Code |
| 0330 | Patching Array | Hard | Code |
| 0331 | Verify Preorder Serialization of a Binary Tree | Medium | Code |
| 0332 | Reconstruct Itinerary | Hard | Code |
| 0333 | Largest BST Subtree | Medium | Code |
| 0334 | Increasing Triplet Subsequence | Medium | Code |
| 0335 | Self Crossing | Hard | Code |
| 0336 | Palindrome Pairs | Hard | Code |
| 0337 | House Robber III | Medium | Code |
| 0338 | Counting Bits | Easy | Code |
| 0339 | Nested List Weight Sum | Medium | Code |
| 0340 | Longest Substring with At Most K Distinct Characters | Medium | Code |
| 0341 | Flatten Nested List Iterator | Medium | Code |
| 0342 | Power of Four | Easy | Code |
| 0343 | Integer Break | Medium | Code |
| 0344 | Reverse String | Easy | Code |
| 0345 | Reverse Vowels of a String | Easy | Code |
| 0346 | Moving Average from Data Stream | Easy | Code |
| 0347 | Top K Frequent Elements | Medium | Code |
| 0348 | Design Tic-Tac-Toe | Medium | Code |
| 0349 | Intersection of Two Arrays | Easy | Code |
| 0350 | Intersection of Two Arrays II | Easy | Code |
| 0351 | Android Unlock Patterns | Medium | Code |
| 0352 | Data Stream as Disjoint Intervals | Hard | Code |
| 0353 | Design Snake Game | Medium | Code |
| 0354 | Russian Doll Envelopes | Hard | Code |
| 0355 | Design Twitter | Medium | Code |
| 0356 | Line Reflection | Medium | Code |
| 0357 | Count Numbers with Unique Digits | Medium | Code |
| 0358 | Rearrange String k Distance Apart | Hard | Code |
| 0359 | Logger Rate Limiter | Easy | Code |
| 0360 | Sort Transformed Array | Medium | Code |
| 0361 | Bomb Enemy | Medium | Code |
| 0362 | Design Hit Counter | Medium | Code |
| 0363 | Max Sum of Rectangle No Larger Than K | Hard | Code |
| 0364 | Nested List Weight Sum II | Medium | Code |
| 0365 | Water and Jug Problem | Medium | Code |
| 0366 | Find Leaves of Binary Tree | Medium | Code |
| 0367 | Valid Perfect Square | Easy | Code |
| 0368 | Largest Divisible Subset | Medium | Code |
| 0369 | Plus One Linked List | Medium | Code |
| 0370 | Range Addition | Medium | Code |
| 0371 | Sum of Two Integers | Medium | Code |
| 0372 | Super Pow | Medium | Code |
| 0373 | Find K Pairs with Smallest Sums | Medium | Code |
| 0374 | Guess Number Higher or Lower | Easy | Code |
| 0375 | Guess Number Higher or Lower II | Medium | Code |
| 0376 | Wiggle Subsequence | Medium | Code |
| 0377 | Combination Sum IV | Medium | Code |
| 0378 | Kth Smallest Element in a Sorted Matrix | Medium | Code |
| 0379 | Design Phone Directory | Medium | Code |
| 0380 | Insert Delete GetRandom O(1) | Medium | Code |
| 0381 | Insert Delete GetRandom O(1) - Duplicates allowed | Hard | Code |
| 0382 | Linked List Random Node | Medium | Code |
| 0383 | Ransom Note | Easy | Code |
| 0384 | Shuffle an Array | Medium | Code |
| 0385 | Mini Parser | Medium | Code |
| 0386 | Lexicographical Numbers | Medium | Code |
| 0387 | First Unique Character in a String | Easy | Code |
| 0388 | Longest Absolute File Path | Medium | Code |
| 0389 | Find the Difference | Easy | Code |
| 0390 | Elimination Game | Medium | Code |
| 0391 | Perfect Rectangle | Hard | Code |
| 0392 | Is Subsequence | Easy | Code |
| 0393 | UTF-8 Validation | Medium | Code |
| 0394 | Decode String | Medium | Code |
| 0395 | Longest Substring with At Least K Repeating Characters | Medium | Code |
| 0396 | Rotate Function | Medium | Code |
| 0397 | Integer Replacement | Medium | Code |
| 0398 | Random Pick Index | Medium | Code |
| 0399 | Evaluate Division | Medium | Code |
| 0400 | Nth Digit | Medium | Code |
| 0401 | Binary Watch | Easy | Code |
| 0402 | Remove K Digits | Medium | Code |
| 0403 | Frog Jump | Hard | Code |
| 0404 | Sum of Left Leaves | Easy | Code |
| 0405 | Convert a Number to Hexadecimal | Easy | Code |
| 0406 | Queue Reconstruction by Height | Medium | Code |
| 0407 | Trapping Rain Water II | Hard | Code |
| 0408 | Valid Word Abbreviation | Easy | Code |
| 0409 | Longest Palindrome | Easy | Code |
| 0410 | Split Array Largest Sum | Hard | Code |
| 0411 | Minimum Unique Word Abbreviation | Hard | Code |
| 0412 | Fizz Buzz | Easy | Code |
| 0413 | Arithmetic Slices | Medium | Code |
| 0414 | Third Maximum Number | Easy | Code |
| 0415 | Add Strings | Easy | Code |
| 0416 | Partition Equal Subset Sum | Medium | Code |
| 0417 | Pacific Atlantic Water Flow | Medium | Code |
| 0418 | Sentence Screen Fitting | Medium | Code |
| 0419 | Battleships in a Board | Medium | Code |
| 0420 | Strong Password Checker | Hard | Code |
| 0421 | Maximum XOR of Two Numbers in an Array | Medium | Code |
| 0422 | Valid Word Square | Easy | Code |
| 0423 | Reconstruct Original Digits from English | Medium | Code |
| 0424 | Longest Repeating Character Replacement | Medium | Code |
| 0425 | Word Squares | Hard | Code |
| 0426 | Convert Binary Search Tree to Sorted Doubly Linked List | Medium | Code |
| 0427 | Construct Quad Tree | Medium | Code |
| 0428 | Serialize and Deserialize N-ary Tree | Hard | Code |
| 0429 | N-ary Tree Level Order Traversal | Medium | Code |
| 0430 | Flatten a Multilevel Doubly Linked List | Medium | Code |
| 0431 | Encode N-ary Tree to Binary Tree | Hard | Code |
| 0432 | All O`one Data Structure | Hard | Code |
| 0433 | Minimum Genetic Mutation | Medium | Code |
| 0434 | Number of Segments in a String | Easy | Code |
| 0435 | Non-overlapping Intervals | Medium | Code |
| 0436 | Find Right Interval | Medium | Code |
| 0437 | Path Sum III | Medium | Code |
| 0438 | Find All Anagrams in a String | Medium | Code |
| 0439 | Ternary Expression Parser | Medium | Code |
| 0440 | K-th Smallest in Lexicographical Order | Hard | Code |
| 0441 | Arranging Coins | Easy | Code |
| 0442 | Find All Duplicates in an Array | Medium | Code |
| 0443 | String Compression | Medium | Code |
| 0444 | Sequence Reconstruction | Medium | Code |
| 0445 | Add Two Numbers II | Medium | Code |
| 0446 | Arithmetic Slices II - Subsequence | Hard | Code |
| 0447 | Number of Boomerangs | Medium | Code |
| 0448 | Find All Numbers Disappeared in an Array | Easy | Code |
| 0449 | Serialize and Deserialize BST | Medium | Code |
| 0450 | Delete Node in a BST | Medium | Code |
| 0451 | Sort Characters By Frequency | Medium | Code |
| 0452 | Minimum Number of Arrows to Burst Balloons | Medium | Code |
| 0453 | Minimum Moves to Equal Array Elements | Easy | Code |
| 0454 | 4Sum II | Medium | Code |
| 0455 | Assign Cookies | Easy | Code |
| 0456 | 132 Pattern | Medium | Code |
| 0457 | Circular Array Loop | Medium | Code |
| 0458 | Poor Pigs | Hard | Code |
| 0459 | Repeated Substring Pattern | Easy | Code |
| 0460 | LFU Cache | Hard | Code |
| 0461 | Hamming Distance | Easy | Code |
| 0462 | Minimum Moves to Equal Array Elements II | Medium | Code |
| 0463 | Island Perimeter | Easy | Code |
| 0464 | Can I Win | Medium | Code |
| 0465 | Optimal Account Balancing | Hard | Code |
| 0466 | Count The Repetitions | Hard | Code |
| 0467 | Unique Substrings in Wraparound String | Medium | Code |
| 0468 | Validate IP Address | Medium | Code |
| 0469 | Convex Polygon | Medium | Code |
| 0470 | Implement Rand10() Using Rand7() | Medium | Code |
| 0471 | Encode String with Shortest Length | Hard | Code |
| 0472 | Concatenated Words | Hard | Code |
| 0473 | Matchsticks to Square | Medium | Code |
| 0474 | Ones and Zeroes | Medium | Code |
| 0475 | Heaters | Medium | Code |
| 0476 | Number Complement | Easy | Code |
| 0477 | Total Hamming Distance | Medium | Code |
| 0478 | Generate Random Point in a Circle | Medium | Code |
| 0479 | Largest Palindrome Product | Hard | Code |
| 0480 | Sliding Window Median | Hard | Code |
| 0481 | Magical String | Medium | Code |
| 0482 | License Key Formatting | Easy | Code |
| 0483 | Smallest Good Base | Hard | Code |
| 0484 | Find Permutation | Medium | Code |
| 0485 | Max Consecutive Ones | Easy | Code |
| 0486 | Predict the Winner | Medium | Code |
| 0487 | Max Consecutive Ones II | Medium | Code |
| 0488 | Zuma Game | Hard | Code |
| 0489 | Robot Room Cleaner | Hard | Code |
| 0490 | The Maze | Medium | Code |
| 0491 | Non-decreasing Subsequences | Medium | Code |
| 0492 | Construct the Rectangle | Easy | Code |
| 0493 | Reverse Pairs | Hard | Code |
| 0494 | Target Sum | Medium | Code |
| 0495 | Teemo Attacking | Easy | Code |
| 0496 | Next Greater Element I | Easy | Code |
| 0497 | Random Point in Non-overlapping Rectangles | Medium | Code |
| 0498 | Diagonal Traverse | Medium | Code |
| 0499 | The Maze III | Hard | Code |
| 0500 | Keyboard Row | Easy | Code |