---|------------------|-----------|-------------------|--------|----------|------|--------------|--------- 1|two-sum|Medium|Java,java,java|57ms,6ms,6ms|Array,Hash Table| | 2|Add Two Numbers|Medium|C++,java|36ms,4ms|Linked List, Math|| 3|Longest Substring Without Repeating Characters|Medium|C++,java,java|16ms,24ms,7ms|Hash Table,Two Pointers,String|| 4|Median of Two Sorted Arrays|Hard|C++|44ms|Divied&Conquer, Array, Binay Search|| 5|Longest Palindromic Substring|Medium|C++|92ms|String|| 6 |ZigZag Conversion| Easy | C++,java| 20ms , 32ms | String | |
7 |Reverse Integer| Easy | C++, C++,java,java |8ms,,2ms,2ms|Math| | | 8|String to Integer (atoi)|Easy|C++,java,java|12ms,5ms,5ms|Math,String| 9 |Palindrome Number|Easy | C++,java | 72ms,13ms |Math | | | 10 |Regular Expression Matching|Hard|java java|6ms, 121ms|DP, Backtracking, String|| 11|Container With Most Water|Medium|C++|28ms|Array, Two Pointers|| 12|Integer to Roman|Medium|C++,java|32ms,7ms|Math,String|| 13 | Roman to Integer | Easy | C++,java,java | 40ms,16ms,9ms | Math, String | |
14 |Longest Common Prefix|Easy|C++,java |4ms,1ms|String | |
15 | 3Sum |Medium|C++ C++ | 64ms,56ms|String,Two ponter | | | 16 | 3Sum Closest|Medium |C++| 20ms | String,Two ponter | |
17|Letter Combinations of a Phone Number|Medium|C++,java|0ms,1ms|Backtracking, String|| 18|4Sum|Medium|C++,java|128ms,12ms|Array, Hash Table, Two Pointers|| 19 | Remove Nth Node From End of List | Easy |C++ | 4ms | Linked List, Two pointer | |
20 | Valid Parentheses | Easy | C++ C++ | 4ms, 0ms | Stack, String | |
21 | Merge Two Sorted Lists | Easy | C++,java | 12ms ,1ms | Linked List | | | 22 | Generate Parentheses | Medium | C++,java | 0ms,2ms | String, Backtracking | | | 23 |Merge k Sorted Lists|Hard|java,java|4ms,4ms|Divide and Conquer, Linked List, Heap|| 24 | Swap Nodes in Pairs | Medium | C++ ,java | 4ms,0ms | Linked List | |
25|Reverse Nodes in k-Group|Hard|java1,java2,java3|1ms,1ms,2ms|Linked List|| 26 | Remove Duplicates from Sorted Array | Easy | C++,java | 32ms ,2ms | Array, Two pointer | | 27 | Remove Element| Easy | C++ | 4ms | Array, Two pointer | | | 28 | Implement strStr() | Easy | C++,java | 4ms ,1ms | String, Two pointer | | | 29|Divide Two Integers|Medium|C++|12ms|Math, Binary Search|| 30 |Substring with Concatenation of All Words|Hard|c++|508ms|Hash Table, Two Pointers, String|| 31|Next Permutation|Medium|C++|12ms|Array|| 32|Longest Valid Parentheses|Hard|C++|12ms|DP, String| 33|Search in Rotated Sorted Array|Hard|C++|4ms|Array, Binary Search|| 34|Search for a Range|Medium|c++|12ms|Binary Search, Array| 35 | Search Insert Position | Medium |C++ java | 8ms , 0ms | Array, Binary Search | | | 36|Valid Sudoku|Easy|java|4ms|Hash Table|| 37|Sudoku Solver|Hard|java|25ms|Backtracking, Hash Table|| 38 | Count and Say| Easy | C++,java | 8ms,2ms |String | | | 39 | Combination Sum | Medium | C++ | 144ms |Array, Backtracking | | | 40 | Combination Sum II | Medium | C++ | 424ms | Array, Backtracking | | | | 41|First Missing Positive|Hard|C++ Python|4ms, 40ms|Array| 42|Trapping Rain Water|Medium|C++|8ms|Array, Stack,Two Pointers|| 43|Multiply Strings|Medium|C++ Python|8ms, 536ms|Math, String|| 44|Wildcard Matching|Hard|java|5ms|DP, Backtracking, Greedy, String|| 45|Jump Game II|Hard|java|4ms|Array, Greedy|| 46|Permutations|Medium|C++,java|16ms,4ms|Backtracking|| 47|Permutations II|Medium|C++,java|32ms,4ms|Backtracking|| 48 | Rotate Image | Medium | C++ | 4ms | Array | | | 49 |Group Anagrams|Medium|java|34ms|Hash Table, String|| 50 |Pow(x, n)|Medium|cpp,java|4ms, 2ms|Math, Binary Search|| 51|N-Queens|Hard|java,java|8ms,4ms|BackTracking|| 52|N-Queens II|Hard|java|7ms|BackTracking|| 53 | Maximum Subarray | Medium | C++ C++ | 12ms, 12ms | Divide&Conquer, Array, DP| | | 54 | Spiral Matrix | Medium | C++,java | 0ms,0ms |Array | | | 55|Jump Game|Medium|java|4ms|Array, Greedy|| 56|Merge Intervals|Hard|C++|592ms|Array, Sort| 57|Insert Interval|Hard|C++|584ms|Array, Sort|| 58 | Length of Last Word | Easy |C++,java | 4ms ,0ms |String | | | 59 | Spiral Matrix II | Medium | C++ | 4ms | Array | | | 60|Permutation Sequence|Medium|c++|0ms|BackTracing,Math|| 61|Rotate List|Medium|C++|12ms|Linked List, Two Pointers|| 62|Unique Paths|Medium|C++|0ms|Array,DP|| 63|Unique Paths II|Medium|java,java|1ms,2ms|Array, DP|| 64|Minimum Path Sum|Medium|C++|28ms|Array,DP|| 65|Valid Number|Hard|java,java|52ms,5ms|String, Math|| 66 | Plus One| Easy | C++ ,java | 4ms ,0ms |Array,Math | | 67 | Add Binary | Easy | C++ ,java | 4ms ,4ms | Math, String | | | 68|Text Justification|Hard|java|1ms|String|| 69|Sqrt(x)|Medium|C++,java,java|12ms,4ms,3ms|Math, Binary Search|| 70 | Climbing Stairs | Easy | C++ | 0ms | DP | | | 71|Simplify Path|Medium|C++|12ms|Stack,String|| 72|Edit Distance|Medium|C++|20ms|DP, String|| 73|Set Matrix Zeroes|Medium|C++|92ms|Array|| 74 | Search a 2D Matrix | Medium | C++ | 12ms | Array, Binary Search | | | 75 | Sort Colors| Medium | C++ | 4ms | Array, Sort, Two pointer | | | 76|Minimum Window Substring|Hard|java|15ms|Hash Table, Two pointers, String|| 77|Combinations|Medium|C++,java|8ms,3ms|BackTrack|| 78 |Subsets| Medium | C++, C++ ,java | 8ms,8ms,2ms | Array, Backtracting, Bit | | | 79|Word Search|Medium|C++|76ms|Array, BackTracking|| 80|Remove Duplicates from Sorted Array II|Medium|C++|16ms|Array,Two pointers|| 81 | Search in Rotated Sorted Array II|Medium|cpp|11ms|Array, Binary Search|| 82 |Remove Duplicates from Sorted List II|Medium|cpp,java|8ms,1ms|Linked List|| 83 | Remove Duplicates from Sorted List | Easy | C++ | 16ms | Linked List | | | 84|Largest Rectangle in Histogram|Hard|C++,java|24ms, 34ms|Array, Stack|| 85|Maximal Rectangle|Hard|java|32ms|DP, Array, Hash Table, Two pointers|| 86|Partition List|Medium|C++|8ms|Linked List, Two Pointers|| 87|Scramble String|Hard|java|9ms|DP, String|| 88 | Merge Sorted Array |Easy | C++ C++ | 0ms,4ms | Array, Two pointer | | | 89|Gray Code|Medium|java,java|2ms,16ms|BackTracking|| 90|Subsets II|Medium|C++|8ms|Array, BackTracking|| 91|Decode Ways|Medium|C++|4ms|DP,String|| 92|Reverse Linked List II|Medium|C++|4ms|Linked List|| 93|Restore IP Addresses|Medium|C++ java|4ms,4ms|BackTracking, String|| 94 | Binary Tree Inorder Traversal| Medium |C++ | 0ms | Tree, Hash Table, Stack | | | 95|Unique Binary Search Trees II|Medium|java|3ms|DP, Tree|| 96|Unique Binary Search Trees|Medium|java|0ms|Tree,DP|| 97|Interleaving String|Hard|C++|8ms|DP, String|| 98|Validate Binary Search Tree|Medium|java,java|1ms,1ms|Tree,DFS|| 99|Recover Binary Search Tree|Hard|java|3ms|DFS, Tree|| 100 | Same Tree |Easy | C++ | 0ms |DFS,Tree | | | 101 | Symmetric Tree | Easy | C++ | 4ms |DFS,Tree | | | 102 | Binary Tree Level Order Traversal | Easy| C++ | 8ms | BFS,Tree | | | 103|Binary Tree Zigzag Level Order Traversal|Medium|java|2ms|BFS,Tree,Stack|| 104 | Maximum Depth of Binary Tree | Easy | C++,java | 8ms ,1ms | DFS,Tree | | | 105|Construct Binary Tree from Preorder and Inorder Traversal|Medium|java|19ms|Tree, Array, DFS|| 106|Construct Binary Tree from Inorder and Postorder Traversal|Medium|java|20ms|Tree, Array, DFS|| 107|Binary Tree Level Order Traversal II|Easy|C++ java|8ms,2ms|Tree, BFS|| 108|Convert Sorted Array to Binary Search Tree|Medium|C++,java|20ms,1ms|Tree, DFS|| 109|Convert Sorted List to Binary Search Tree|Medium|java|1ms|DFS, Linked List|| 110 | Balanced Binary Tree | Easy | C++ ,java |16ms ,2ms | DFS,Tree | | | 111 | Minimum Depth of Binary Tree | Easy |C++ C++ ,java,java | 20ms,12ms,1ms,1ms | DFS,BFS,Tree | | | 112 |Path Sum|Easy|java|1ms|Tree, DFS|| 113 |Path Sum II|Medium|java|4ms|Tree, DFS|| 114|Flatten Binary Tree to Linked List|Medium|java,java|3ms,1ms|DFS,Tree|| 115|Distinct Subsequences|Hard|java,java|35ms,20ms|DP, String|| 116 | Populating Next Right Pointers in Each Node| Medium| C++,java | 24ms ,1ms | DFS,Tree | 117|Populating Next Right Pointers in Each Node II|Hard|java,java|1ms,13ms|DFS, Tree|| 118 | Pascal's Triangle| Easy | C++ C++ ,java | 4ms,0ms ,1ms | Array | | | 119 | Pascal's Triangle II| Easy | C++ ,java | 0ms ,3ms |Array | | | 120|Triangle|Medium|C++|DP,Array|120ms|| 121 | Best Time to Buy and Sell Stock | Medium | C++ | 8ms | Array,DP | | | 122 | Best Time to Buy and Sell Stock II | Medium | C++ | 8ms | Array, Greedy | | 123|Best Time to Buy and Sell Stock III|Hard|java|2ms|DP, Array|| 124|Binary Tree Maximum Path Sum|Hard|java|2ms|DFS, Tree|| 125 | Valid Palindrome| Easy | C++ ,java ,java | 16ms,8ms ,8ms | Two pointer, String | | | 126|Word Ladder II|Hard|java|163ms|Array, Backtracking, BFS, String|| 127|Word Ladder|Medium|C++|356ms|---|| 128|Longest Consecutive Sequence|Hard|C++|12ms|Array,Union FInd|| 129|Sum Root to Leaf Numbers|Medium|java|1ms|Tree, DFS|| 130|Surrounded Regions|Medium|java|7ms|BFS, Union Find|| 131|Palindrome Partitioning|Medium|java|6ms|Backtracking|| 132|Palindrome Partitioning II|Hard|java|20ms|DP|| 133|Clone Graph|Medium|java,java|5ms,10ms|DFS, BFS, Graph|| 134|Gas Station|Medium|C++|8ms|Greedy|| 135|Candy|Hard|java|5ms|Greedy|| 136 | Single Number |Medium | C++ C++ ,java,java,java | 60ms,20ms,29ms,22ms,2ms |Hash Table, Bit | | | 137 | Single Number II |Medium | C++ C++,java |32ms,12ms,1ms | Bit | | | 138|Copy List with Random Pointer|Hard|java|4ms|Hash Table, Linked List|| 139|Word Break|Medium|C++|8ms|---|| 140|Word Break II|Hard|java|13ms|DP, BackTracking|| 141 | Linked List Cycle | Medium | C++ | 12ms |Two pointer, Linked List | | | 142|Linked List Cycle II|Medium|C++|12ms|Linked List, Two pointers|| 143|Reorder List|Medium|java|3ms|Linked List|| 144 | Binary Tree Preorder Traversal | Medium | C++ | 0ms | Stack, Tree | | | 145 | Binary Tree Postorder Traversal | Hard | C++ C++ | 0ms ,0ms | Stack, Tree | | | 146|LRU Cache|Hard|java|29ms|Design|| 147 | Insertion Sort List | Medium | C++ | 80ms |Linked List, Sort | | | 148 | Sort List | Medium| C++ | 68ms | Linked List, Sort | | 149|Max Points on a Line|Hard|java|46ms|Hash Table, Math|| 150|Evaluate Reverse Polish Notation|Medium|C++|16ms|Stack|| 151|Reverse Words in a String|Medium|C++,C++,java,java|8ms,12ms,13ms,9ms|String|| 152|Maximum Product Subarray|Medium|C++,java|4ms, 1ms|Array,DP|| 153|Find Minimum in Rotated Sorted Array|Medium|++,java,c++|16ms,1ms, 4ms|Array, Binary Search| 154|Find Minimum in Rotated Sorted Array II|Hard|cpp,java|12ms,1ms|Array, Binary Search|| 155 | Min Stack | Easy | C++ | 28ms | Stack | | | 156|Binary Tree Upside Down|Medium|java|1ms|Tree|| 157|Read N Characters Given Read4|Easy|java|2ms|String|| 158|Read N Characters Given Read4 II - Call multiple times|Hard|java|3ms|String|| 159|Longest Substring with At Most Two Distinct Characters|Hard|java|20ms|Hash Table, String, Two pointer| 160 | Intersection of Two Linked Lists | Easy | C++ | 52ms | Linked List | | | 161|One Edit Distance|Medium|java|2ms|String|| 162 | Find Peak Element | Medium | C++ , C++, java | 8ms, 8ms, 0ms |Array, Binary Search | | | 163|Missing Ranges|Medium|java|9ms|Array|| 164|Maximum Gap|Hard|java,java|5ms,7ms|Sort|| 165 | Compare Version Numbers | Easy | Java | 4ms | String | | | 166|Fraction to Recurring Decimal|Medium|java|4ms|Hash Table, Math|| 167|Two Sum II - Input array is sorted|Medium|java|1ms|Array, Two Pointers, Binary Search|| 168 | Excel Sheet Column Title | Easy | C++ | 0ms | Math | | | 169 | Majority Element | Easy | C++ , C++, C++ ,java | 24ms,20ms,20ms ,2ms | Divide&Conquer, Bit, Array | | | 170|Two Sum III - Data structure design|Easy|java|389ms|Hash Table, Design|| 171 | Excel Sheet Column Number | Easy |C++,java | 12ms ,3ms | Math | | | 172 | Factorial Trailing Zeroes | Easy | C++ | 4ms | Math | | | 173|Binary Search Tree Iterator|Medium|java|6ms|Tree,Stack,Design|| 174|Dungeon Game|Hard|java|5ms|DP, Binary Search|| 179 |Largest Number|Medium|java,java|Sort|121ms,130ms|| 186|Reverse Words in a String II|Medium|java|3ms|String|| 187|Repeated DNA Sequences|Medium|java|51ms|Hash Table, Bits Manipulation|| 188|Best Time to Buy and Sell Stock IV|Hard|java|13ms|DP, Array|| 189 | Rotate Array | Easy | C++, C++ ,java | 24ms,24ms,1ms |Array | | | 190 | Reverse Bits | Easy | C++ | 8ms |Bit | | | 191 | Number of 1 Bits | Easy | C++ C++ | 8ms |Bit | | | 198|House Robber|Easy|C++|0ms|DP|| 199|Binary Tree Right Side View|Medium|java,java|Tree,DFS,BFS|2ms,2ms|| 200|Number of Islands|Medium|java|3ms|DFS, BFS, Union Find|| 201|Bitwise AND of Numbers Range|Medium|java|7ms|Bit Manipulation|| 202 | Happy Number | Easy | C++ | 4ms | Hash Table, Math | | | 203 | Remove Linked List Elements | Easy |C++ ,java | 32ms ,2ms | Linked List | | | 204 | Count Primes | Easy | C++ C++ | 392ms, 216ms | Hash Table, Math | | | 205 | Isomorphic Strings | Easy| Python | 76ms |Hash Table | | | 206 | Reverse Linked List | Easy | C++ ,java | 8ms,0ms |Linked List | | | 207|Course Schedule|Medium|java|34ms|DFS,BFS,Graph,Topological Sort|| 208|Implement Trie (Prefix Tree) |Medium|java|20ms|Trie,Desigh|| 209|Minimum Size Subarray Sum|Medium|C++|4ms|Array,Two pointers,Binary Search| 210|Course Schedule II|Medium|java|9ms|DFS,BFS,Graph,Topological Sort|| 211|Add and Search Word - Data structure design|Medium|java|23ms|Backtracking, Trie, Design|| 212|Word Search II|Hard|java|119ms|Trie, Backtracking|| 213|House Robber II|Medium|C++|0ms|DP|| 214|Shortest Palindrome|Hard|python|276ms|String| 215 | Kth Largest Element in an Array |Medium| C++| 8ms | Divide&Conquer, Heap | | | 216|Combination Sum III|Medium|java|1ms|Array, Backtracking|| 217|Contains Duplicate|Easy|C++C++|108ms, 36ms|Array, Hash Table|| 218|The Skyline Problem|Hard|java|15ms|Binary Index Tree, Segment Tree, Heap, Divide and Conquer|| 219|Contains Duplicate II|Easy|C++C++C++|108ms, 32ms, 12ms|Array, Hash Table|| 220|Contains Duplicate III|Medium|java|48ms|Binary Search Tree|| 221|Maximal Square|Medium|java|9ms|DP|| 222|Count Complete Tree Nodes|Medium|java|114ms|Tree, Binary Search|| 223|Rectangle Area|Easy|C++|32ms|Math|| 224|Basic Calculator|Medium|C++|20ms|Stack,Math|| 225|Implement Stack using Queues|Easy|C++,java|0ms,95ms|Stack|| 226|Invert Binary Tree|Medium|C++|0ms|Tree|| 227|Basic Calculator II|Medium|C++|24ms|String|| 228|Summary Ranges|Easy|C++,java|0ms,1ms|Array|| 229 |Majority Element II|Medium|java|3ms|Array|| 230|Kth Smallest Element in a BST|Medium|C++|24ms|Tree, Binary Search|| 231|Power of Two|Easy|C++|8ms|Math, Bit|| 232|Implement Queue using Stacks|Easy|C++|0ms|Stack|| 233|Number of Digit One|Medium|java|Math|0ms|| 234|Palindrome Linked List|Easy|C++|24ms|Linked List, Two pointer|| 235|Lowest Common Ancestor of a Binary Search Tree|Easy|C++|40ms|Tree|| 236|Lowest Common Ancestor of a Binary Tree|Medium|java|13ms|Tree|| 237|Delete Node in a Linked List|Easy|C++|16ms|Linked List|| 238|Product of Array Except Self|Medium|C++|60ms|Array|| 239|Sliding Window Maximum|Hard|java|25ms|Heap|| 240|Search a 2D Matrix II|Medium|C++|260ms|Divide&Conquer, Binary Search|| 241|Different Ways to Add Parentheses|Medium|C++|4ms|Divide and Conquer|| 242|Valid Anagram|Easy|C++Python|12ms ,152ms|Hash Table, Sort|| 243|Shortest Word Distance|Easy|java|5ms|Array|| 244|Shortest Word Distance II|Medium|java|22ms|Array|| 245|Shortest Word Distance III|Medium|java|2ms|Array|| 246|Strobogrammatic Number|Easy|java|1ms|Hash Table, Math|| 247|Strobogrammatic Number II|Medium|java,java|100ms, 6ms|Math,Recursion|| 248|Strobogrammatic Number III|Hard|java|62ms|Math, Resursion|| 249|Group Shifted Strings|Easy|java|11ms|Hash Table, String| 250|Count Univalue Subtrees|Medium|java|1ms|Tree|| 251|Flatten 2D Vector|Medium|java|5ms|Design|| 252|Meeting Rooms|Easy|java|15ms|Sort|| 253|Meeting Rooms II|Medium|java,java|5ms, 18ms|Heap, Greedy, Sort|| 254|Factor Combinations|Medium|java,java|234ms,2ms|Hash Table, String|| 255|Verify Preorder Sequence in Binary Search Tree|Medium|java|37ms|Stack, Tree|| 256|Paint House|Medium|java|1ms|DP|| 257|Binary Tree Paths|Easy|C++ java|4ms,3ms|DFS,Trss|| 258|Add Digits|Easy|C++|8ms|Math|| 259|3Sum Smaller|Medium|java|5ms|Array, Two Pointers|| 260|Single Number III|Medium|C++C++|32ms,20ms|Bit|| 261|Graph Valid Tree|Medium|java|3ms|DFS, BFS, Graph, Union Find|| 263|Ugly Number|Easy|C++|8ms|Math|| 264|Ugly Number II|Medium|java,java|11ms. 9ms|DP, Heap, Math|| 265|Paint House II|Hard|java|7ms|DP|| 266|Palindrome Permutation|Easy|java,java|3ms,1ms|Hash Table|| 267|Palindrome Permutation II|Medium|java|7ms|Backtracking|| 268|Missing Number|Medium|C++C++|36ms,76ms|Array, Math, Bit|| 269|Alien Dictionary|Hard|java|12ms|Graph, Topological Sort|| 270|Closest Binary Search Tree Value|Easy|java|0ms|Tree, Binary Search|| 271|Encode and Decode Strings|Medium|java|15ms|String|| 272|Closest Binary Search Tree Value II|Hard|java|5ms|Tree, Stack|| 273|Integer to English Words|Medium|C++|8ms|Math, String|| 274 |H-Index|Medium|C++, java|4ms, 2ms|Hash Table, Sort|| 275|H-Index II|Medium|java|162ms|Binary Search|| 276|Paint Fence|Easy|java|0ms|DP|| 277|Find the Celebrity|Medium|java|14ms|Array|| 278|First Bad Version|Medium|C++,java|0ms, 18ms|Binary Search|| 279|Perfect Squares|Medium|java|DP, BFS,Math|69ms|| 280|Wiggle Sort|Medium|java|2ms|Array, Sort|| 281|Zigzag Iterator|Medium|java|4ms|Design|| 282|Expression Add Operators|Hard|java|275ms|Divide and Conquer|| 283|Move Zeroes|Easy|C++|103ms|Array, Two pointer|| 284|Peeking Iterator|Medium|java|107ms|Design|| 285|Inorder Successor in BST|Medium|java|5ms|Tree|| 286|Walls and Gates|Medium|java|8ms|BFS|| 287|Find the Duplicate Number|Hard|C++|24ms|Array, Two pointers, Binary Search|| 288|Unique Word Abbreviation|Easy|java|51ms|Hash Table, Design|| 289 |Game of Life|Medium|java|1ms|Array|| 290|Word Pattern|Easy|C++,java|0ms,3ms|Hash Table|| 291|Word Pattern II|Hard|java|97ms|Backtracking|| 292|Nim Game|Easy|C++Python,java|0ms, 48ms, 0ms||| 293|Flip Game|Easy|java|1ms|String|| 294|Flip Game II|Medium|java,java,java|306ms, 204ms, 19ms|Backtracking|| 295|Find Median from Data Stream|Hard|java|43ms|Heap, Design|| 296|Best Meeting Point|Hard|java|21ms|Math, Sort|| 297|Serialize and Deserialize Binary Tree|Hard|java|24ms|Design, Tree|| 298|Binary Tree Longest Consecutive Sequence|Medium|java|2ms|Tree|| 299|Bulls and Cows|Easy|C++|8ms|Hash Table|| 300|Longest Increasing Subsequence|Medium|java|36ms|DP, Binary Search|| 301|Remove Invalid Parentheses|Hard|java|106ms|DFS, BFS|| 302|Smallest Rectangle Enclosing Black Pixels|Hard|java,java|5ms, 1ms|Binary Search|| 303|Range Sum Query - Immutable|Easy|C++,java|608ms,3ms|DP|| 304|Range Sum Query 2D - Immutable|Medium|java|9ms|DP|| 305|Number of Islands II|Hard|java|5ms|Union Find|| 306|Additive Number|Medium|java|3ms|---|| 307|Range Sum Query - Mutable|Hard|java|15ms|Binary Indexed Tree, Segment Tree|| 308|Range Sum Query 2D - Mutable|Medium|java,java|17ms, 20ms|BIT, Segment Tree|| 309|Best Time to Buy and Sell Stock with Cooldown|Medium|java|3ms|DP| 310|Minimum Height Trees|Medium|java|79ms|Graph, BFS|| 311|Sparse Matrix Multiplication|Medium|java,java|64ms, 112ms|Hash Table|| 312|Burst Balloons|Hard|java|15ms|Divide & Conquer, DP| 313|Super Ugly Number |Medium|java|31ms|Math, Heap|| 314|Binary Tree Vertical Order Traversal|Medium|java|6ms|Hash Table|| 315|Count of Smaller Numbers After Self|Hard|java|52ms|Binary Search|| 316|Remove Duplicate Letters|Hard|java|37ms|Stack, Greedy|| 317|Shortest Distance from All Buildings|Hard|java|75ms|BFS|| 318|Maximum Product of Word Lengths|Medium|java|40ms|Bit Manipulation| 319|Bulb Switcher|Medium|C++|0ms|Math. Brainteaser|| 320|Generalized Abbreviation|Medium|java|100ms|Backtracking, Bit Manipulation|| 321|Create Maximum Number|Hard|java|19ms|DP, Greedy|| 322|Coin Change|Medium|java|30ms|DP|| 323|Number of Connected Components in an Undirected Graph|Medium|java|2ms|DFS, BFS, Graph, Union Find|| 324|Wiggle Sort II|Medium|java|6ms|Sort|| 325|Maximum Size Subarray Sum Equals k|Easy|java|38ms|Hash Table|| 326|Power of Three|Easy|c++|128ms|Math| 327|Count of Range Sum|Hard|java|15ms|Divide & Conquer, Binary Search Tree| 328|Odd Even Linked List|Easy|C++|20ms|Linked List|| 329|Longest Increasing Path in a Matrix|Hard|java|16ms|DFS, Topological Sort, Memoization|| 330|Patching Array|Medium|java|1ms|Greedy|| 331|Verify Preorder Serialization of a Binary Tree|Medium|java,java|10ms,25ms|Stack|| 332|Reconstruct Itinerary|Medium|java|14ms|DFS, Graph|| 333|Largest BST Subtree|Medium|java|2ms|Tree|| 334 |Increasing Triplet Subsequence|Medium|java|1ms|---|| 335|Self Crossing|Medium|java|0ms|Math|| 336|Palindrome Pairs|Hard|java|152ms|Hash Table, String, Trie|| 337|House Robber III|Medium|java|1ms|DFS, Tree|| 338|Counting Bits|Medium|java|5ms|DP, Bit Manipulation|| 339|Nested List Weight Sum|Easy|java|2ms|DFS|| 340|Longest Substring with At Most K Distinct Characters|Hard|java|14ms|Hash Table, String|| 341|Flatten Nested List Iterator|Medium|java|9ms|Stack, Design|| 342|Power of Four|Easy|java|2ms|Bit Manipulation|| 343|Integer Break|Medium|java,java|3ms, 0ms|DP, Math|| 344|Reverse String|Easy|java|2ms|---|| 345|Reverse Vowels of a String|Easy|java|17ms|Two pointers|| 346|Moving Average from Data Stream|Easy|java|162ms|Design, Queue|| 347|Top K Frequent Elements|Medium|java,java|123ms, 52ms|HashMap, Heap|| 348|Design Tic-Tac-Toe|Medium|java|136ms|Design|| 349|Intersection of Two Arrays|Easy|java|6ms|Binary Search, Hash Table, Two Pointers, Sort||