| 1 |
Two Sum |
Easy |
| 2 |
Add Two Numbers |
Medium |
| 3 |
Longest Substring Without Repeating Characters |
Medium |
| 4 |
Median of Two Sorted Arrays |
Hard |
| 5 |
Longest Palindromic Substring |
Medium |
| 6 |
ZigZag Conversion |
Medium |
| 7 |
Reverse Integer |
Easy |
| 8 |
String to Integer (atoi) |
Medium |
| 9 |
Palindrome Number |
Easy |
| 10 |
Regular Expression Matching |
Hard |
| 11 |
Container With Most Water |
Medium |
| 12 |
Integer to Roman |
Medium |
| 13 |
Roman to Integer |
Easy |
| 14 |
Longest Common Prefix |
Easy |
| 15 |
3Sum |
Medium |
| 16 |
3Sum Closest |
Medium |
| 17 |
Letter Combinations of a Phone Number |
Medium |
| 18 |
4Sum |
Medium |
| 19 |
Remove Nth Node From End of List |
Medium |
| 20 |
Valid Parentheses |
Easy |
| 21 |
Merge Two Sorted Lists |
Easy |
| 22 |
Generate Parentheses |
Medium |
| 23 |
Merge k Sorted Lists |
Hard |
| 24 |
Swap Nodes in Pairs |
Medium |
| 25 |
Reverse Nodes in k-Group |
Hard |
| 26 |
Remove Duplicates from Sorted Array |
Easy |
| 27 |
Remove Element |
Easy |
| 28 |
Implement strStr() |
Easy |
| 29 |
Divide Two Integers |
Medium |
| 30 |
Substring with Concatenation of All Words |
Hard |
| 31 |
Next Permutation |
Medium |
| 32 |
Longest Valid Parentheses |
Hard |
| 33 |
Search in Rotated Sorted Array |
Medium |
| 34 |
Search for a Range |
Medium |
| 35 |
Search Insert Position |
Easy |
| 36 |
Valid Sudoku |
Medium |
| 37 |
Sudoku Solver |
Hard |
| 38 |
Count and Say |
Easy |
| 39 |
Combination Sum |
Medium |
| 40 |
Combination Sum II |
Medium |
| 41 |
First Missing Positive |
Hard |
| 42 |
Trapping Rain Water |
Hard |
| 43 |
Multiply Strings |
Medium |
| 44 |
Wildcard Matching |
Hard |
| 45 |
Jump Game II |
Hard |
| 46 |
Permutations |
Medium |
| 47 |
Permutations II |
Medium |
| 48 |
Rotate Image |
Medium |
| 49 |
Group Anagrams |
Medium |
| 50 |
Pow(x, n) |
Medium |
| 51 |
N-Queens |
Hard |
| 52 |
N-Queens II |
Hard |
| 53 |
Maximum Subarray |
Easy |
| 54 |
Spiral Matrix |
Medium |
| 55 |
Jump Game |
Medium |
| 56 |
Merge Intervals |
Medium |
| 57 |
Insert Interval |
Hard |
| 58 |
Length of Last Word |
Easy |
| 59 |
Spiral Matrix II |
Medium |
| 60 |
Permutation Sequence |
Medium |
| 61 |
Rotate List |
Medium |
| 62 |
Unique Paths |
Medium |
| 63 |
Unique Paths II |
Medium |
| 64 |
Minimum Path Sum |
Medium |
| 65 |
Valid Number |
Hard |
| 66 |
Plus One |
Easy |
| 67 |
Add Binary |
Easy |
| 68 |
Text Justification |
Hard |
| 69 |
Sqrt(x) |
Easy |
| 70 |
Climbing Stairs |
Easy |
| 71 |
Simplify Path |
Medium |
| 72 |
Edit Distance |
Hard |
| 73 |
Set Matrix Zeroes |
Medium |
| 74 |
Search a 2D Matrix |
Medium |
| 75 |
Sort Colors |
Medium |
| 76 |
Minimum Window Substring |
Hard |
| 77 |
Combinations |
Medium |
| 78 |
Subsets |
Medium |
| 79 |
Word Search |
Medium |
| 80 |
Remove Duplicates from Sorted Array II |
Medium |
| 81 |
Search in Rotated Sorted Array II |
Medium |
| 82 |
Remove Duplicates from Sorted List II |
Medium |
| 83 |
Remove Duplicates from Sorted List |
Easy |
| 84 |
Largest Rectangle in Histogram |
Hard |
| 85 |
Maximal Rectangle |
Hard |
| 86 |
Partition List |
Medium |
| 87 |
Scramble String |
Hard |
| 88 |
Merge Sorted Array |
Easy |
| 89 |
Gray Code |
Medium |
| 90 |
Subsets II |
Medium |
| 91 |
Decode Ways |
Medium |
| 92 |
Reverse Linked List II |
Medium |
| 93 |
Restore IP Addresses |
Medium |
| 94 |
Binary Tree Inorder Traversal |
Medium |
| 95 |
Unique Binary Search Trees II |
Medium |
| 96 |
Unique Binary Search Trees |
Medium |
| 97 |
Interleaving String |
Hard |
| 98 |
Validate Binary Search Tree |
Medium |
| 99 |
Recover Binary Search Tree |
Hard |
| 100 |
Same Tree |
Easy |
| 101 |
Symmetric Tree |
Easy |
| 102 |
Binary Tree Level Order Traversal |
Medium |
| 103 |
Binary Tree Zigzag Level Order Traversal |
Medium |
| 104 |
Maximum Depth of Binary Tree |
Easy |
| 105 |
Construct Binary Tree from Preorder and Inorder Traversal |
Medium |
| 106 |
Construct Binary Tree from Inorder and Postorder Traversal |
Medium |
| 107 |
Binary Tree Level Order Traversal II |
Easy |
| 108 |
Convert Sorted Array to Binary Search Tree |
Easy |
| 109 |
Convert Sorted List to Binary Search Tree |
Medium |
| 110 |
Balanced Binary Tree |
Easy |
| 111 |
Minimum Depth of Binary Tree |
Easy |
| 112 |
Path Sum |
Easy |
| 113 |
Path Sum II |
Medium |
| 114 |
Flatten Binary Tree to Linked List |
Medium |
| 115 |
Distinct Subsequences |
Hard |
| 118 |
Pascal's Triangle |
Easy |
| 119 |
Pascal's Triangle II |
Easy |
| 120 |
Triangle |
Medium |
| 121 |
Best Time to Buy and Sell Stock |
Easy |
| 122 |
Best Time to Buy and Sell Stock II |
Easy |
| 123 |
Best Time to Buy and Sell Stock III |
Hard |
| 124 |
Binary Tree Maximum Path Sum |
Hard |
| 125 |
Valid Palindrome |
Easy |
| 126 |
Word Ladder II |
Hard |
| 127 |
Word Ladder |
Medium |
| 128 |
Longest Consecutive Sequence |
Hard |
| 129 |
Sum Root to Leaf Numbers |
Medium |
| 130 |
Surrounded Regions |
Medium |
| 131 |
Palindrome Partitioning |
Medium |
| 132 |
Palindrome Partitioning II |
Hard |
| 134 |
Gas Station |
Medium |
| 135 |
Candy |
Hard |
| 136 |
Single Number |
Easy |
| 137 |
Single Number II |
Medium |
| 139 |
Word Break |
Medium |
| 140 |
Word Break II |
Hard |
| 141 |
Linked List Cycle |
Easy |
| 142 |
Linked List Cycle II |
Medium |
| 143 |
Reorder List |
Medium |
| 144 |
Binary Tree Preorder Traversal |
Medium |
| 145 |
Binary Tree Postorder Traversal |
Hard |
| 146 |
LRU Cache |
Medium |
| 147 |
Insertion Sort List |
Medium |
| 148 |
Sort List |
Medium |
| 149 |
Max Points on a Line |
Hard |
| 150 |
Evaluate Reverse Polish Notation |
Medium |
| 151 |
Reverse Words in a String |
Medium |
| 152 |
Maximum Product Subarray |
Medium |
| 153 |
Find Minimum in Rotated Sorted Array |
Medium |
| 154 |
Find Minimum in Rotated Sorted Array II |
Hard |
| 155 |
Min Stack |
Easy |
| 160 |
Intersection of Two Linked Lists |
Easy |
| 162 |
Find Peak Element |
Medium |
| 164 |
Maximum Gap |
Hard |
| 165 |
Compare Version Numbers |
Medium |
| 166 |
Fraction to Recurring Decimal |
Medium |
| 167 |
Two Sum II - Input array is sorted |
Easy |
| 168 |
Excel Sheet Column Title |
Easy |
| 169 |
Majority Element |
Easy |
| 171 |
Excel Sheet Column Number |
Easy |
| 172 |
Factorial Trailing Zeroes |
Easy |
| 173 |
Binary Search Tree Iterator |
Medium |
| 174 |
Dungeon Game |
Hard |
| 179 |
Largest Number |
Medium |
| 187 |
Repeated DNA Sequences |
Medium |
| 188 |
Best Time to Buy and Sell Stock IV |
Hard |
| 189 |
Rotate Array |
Easy |
| 190 |
Reverse Bits |
Easy |
| 191 |
Number of 1 Bits |
Easy |
| 198 |
House Robber |
Easy |
| 199 |
Binary Tree Right Side View |
Medium |
| 200 |
Number of Islands |
Medium |
| 201 |
Bitwise AND of Numbers Range |
Medium |
| 202 |
Happy Number |
Easy |
| 203 |
Remove Linked List Elements |
Easy |
| 204 |
Count Primes |
Easy |
| 205 |
Isomorphic Strings |
Easy |
| 206 |
Reverse Linked List |
Easy |
| 207 |
Course Schedule |
Medium |
| 208 |
Implement Trie (Prefix Tree) |
Medium |
| 209 |
Minimum Size Subarray Sum |
Medium |
| 210 |
Course Schedule II |
Medium |
| 211 |
Add and Search Word - Data structure design |
Medium |
| 212 |
Word Search II |
Hard |
| 213 |
House Robber II |
Medium |
| 214 |
Shortest Palindrome |
Hard |
| 215 |
Kth Largest Element in an Array |
Medium |
| 216 |
Combination Sum III |
Medium |
| 217 |
Contains Duplicate |
Easy |
| 219 |
Contains Duplicate II |
Easy |
| 220 |
Contains Duplicate III |
Medium |
| 221 |
Maximal Square |
Medium |
| 222 |
Count Complete Tree Nodes |
Medium |
| 223 |
Rectangle Area |
Medium |
| 225 |
Implement Stack using Queues |
Easy |
| 226 |
Invert Binary Tree |
Easy |
| 227 |
Basic Calculator II |
Medium |
| 228 |
Summary Ranges |
Medium |
| 229 |
Majority Element II |
Medium |
| 230 |
Kth Smallest Element in a BST |
Medium |
| 231 |
Power of Two |
Easy |
| 232 |
Implement Queue using Stacks |
Easy |
| 234 |
Palindrome Linked List |
Easy |
| 235 |
Lowest Common Ancestor of a Binary Search Tree |
Easy |
| 236 |
Lowest Common Ancestor of a Binary Tree |
Medium |
| 237 |
Delete Node in a Linked List |
Easy |
| 238 |
Product of Array Except Self |
Medium |
| 240 |
Search a 2D Matrix II |
Medium |
| 241 |
Different Ways to Add Parentheses |
Medium |
| 242 |
Valid Anagram |
Easy |
| 257 |
Binary Tree Paths |
Easy |
| 258 |
Add Digits |
Easy |
| 260 |
Single Number III |
Medium |
| 263 |
Ugly Number |
Easy |
| 264 |
Ugly Number II |
Medium |
| 268 |
Missing Number |
Easy |
| 274 |
H-Index |
Medium |
| 275 |
H-Index II |
Medium |
| 279 |
Perfect Squares |
Medium |
| 283 |
Move Zeroes |
Easy |
| 287 |
Find the Duplicate Number |
Medium |
| 289 |
Game of Life |
Medium |
| 290 |
Word Pattern |
Easy |
| 292 |
Nim Game |
Easy |
| 299 |
Bulls and Cows |
Medium |
| 300 |
Longest Increasing Subsequence |
Medium |
| 303 |
Range Sum Query - Immutable |
Easy |
| 304 |
Range Sum Query 2D - Immutable |
Medium |
| 306 |
Additive Number |
Medium |
| 307 |
Range Sum Query - Mutable |
Medium |
| 322 |
Coin Change |
Medium |
| 324 |
Wiggle Sort II |
Medium |
| 326 |
Power of Three |
Easy |
| 328 |
Odd Even Linked List |
Medium |
| 332 |
Reconstruct Itinerary |
Medium |
| 334 |
Increasing Triplet Subsequence |
Medium |
| 342 |
Power of Four |
Easy |
| 344 |
Reverse String |
Easy |
| 345 |
Reverse Vowels of a String |
Easy |
| 347 |
Top K Frequent Elements |
Medium |
| 349 |
Intersection of Two Arrays |
Easy |
| 350 |
Intersection of Two Arrays II |
Easy |
| 367 |
Valid Perfect Square |
Easy |
| 371 |
Sum of Two Integers |
Easy |
| 378 |
Kth Smallest Element in a Sorted Matrix |
Medium |
| 380 |
Insert Delete GetRandom O(1) |
Medium |
| 383 |
Ransom Note |
Easy |
| 384 |
Shuffle an Array |
Medium |
| 387 |
First Unique Character in a String |
Easy |
| 389 |
Find the Difference |
Easy |
| 392 |
Is Subsequence |
Easy |
| 395 |
Longest Substring with At Least K Repeating Characters |
Medium |
| 400 |
Nth Digit |
Easy |
| 401 |
Binary Watch |
Easy |
| 403 |
Frog Jump |
Hard |
| 404 |
Sum of Left Leaves |
Easy |
| 405 |
Convert a Number to Hexadecimal |
Easy |
| 409 |
Longest Palindrome |
Easy |
| 412 |
Fizz Buzz |
Easy |
| 414 |
Third Maximum Number |
Easy |
| 415 |
Add Strings |
Easy |
| 434 |
Number of Segments in a String |
Easy |
| 437 |
Path Sum III |
Easy |
| 438 |
Find All Anagrams in a String |
Easy |
| 441 |
Arranging Coins |
Easy |
| 443 |
String Compression |
Easy |
| 445 |
Add Two Numbers II |
Medium |
| 447 |
Number of Boomerangs |
Easy |
| 448 |
Find All Numbers Disappeared in an Array |
Easy |
| 453 |
Minimum Moves to Equal Array Elements |
Easy |
| 454 |
4Sum II |
Medium |
| 455 |
Assign Cookies |
Easy |
| 458 |
Poor Pigs |
Easy |
| 459 |
Repeated Substring Pattern |
Easy |
| 461 |
Hamming Distance |
Easy |
| 463 |
Island Perimeter |
Easy |
| 475 |
Heaters |
Easy |
| 476 |
Number Complement |
Easy |
| 479 |
Largest Palindrome Product |
Easy |
| 482 |
License Key Formatting |
Easy |
| 485 |
Max Consecutive Ones |
Easy |
| 492 |
Construct the Rectangle |
Easy |
| 496 |
Next Greater Element I |
Easy |
| 500 |
Keyboard Row |
Easy |
| 501 |
Find Mode in Binary Search Tree |
Easy |
| 504 |
Base 7 |
Easy |
| 506 |
Relative Ranks |
Easy |
| 507 |
Perfect Number |
Easy |
| 509 |
Fibonacci Number |
Easy |
| 520 |
Detect Capital |
Easy |
| 521 |
Longest Uncommon Subsequence I |
Easy |
| 530 |
Minimum Absolute Difference in BST |
Easy |
| 532 |
K-diff Pairs in an Array |
Easy |
| 538 |
Convert BST to Greater Tree |
Easy |
| 541 |
Reverse String II |
Easy |
| 543 |
Diameter of Binary Tree |
Easy |
| 551 |
Student Attendance Record I |
Easy |
| 557 |
Reverse Words in a String III |
Easy |
| 561 |
Array Partition I |
Easy |
| 563 |
Binary Tree Tilt |
Easy |
| 566 |
Reshape the Matrix |
Easy |
| 572 |
Subtree of Another Tree |
Easy |
| 575 |
Distribute Candies |
Easy |
| 581 |
Shortest Unsorted Continuous Subarray |
Easy |
| 590 |
N-ary Tree Postorder Traversal |
Easy |
| 594 |
Longest Harmonious Subsequence |
Easy |
| 598 |
Range Addition II |
Easy |
| 599 |
Minimum Index Sum of Two Lists |
Easy |
| 604 |
Design Compressed String Iterator |
Easy |
| 605 |
Can Place Flowers |
Easy |
| 606 |
Construct String from Binary Tree |
Easy |
| 617 |
Merge Two Binary Trees |
Easy |
| 624 |
Maximum Distance in Arrays |
Easy |
| 628 |
Maximum Product of Three Numbers |
Easy |
| 633 |
Sum of Square Numbers |
Easy |
| 637 |
Average of Levels in Binary Tree |
Easy |
| 643 |
Maximum Average Subarray I |
Easy |
| 644 |
Maximum Average Subarray II |
Hard |
| 645 |
Set Mismatch |
Easy |
| 646 |
Maximum Length of Pair Chain |
Medium |
| 647 |
Palindromic Substrings |
Medium |
| 648 |
Replace Words |
Medium |
| 653 |
Two Sum IV - Input is a BST |
Easy |
| 654 |
Maximum Binary Tree |
Medium |
| 655 |
Print Binary Tree |
Medium |
| 657 |
Judge Route Circle |
Easy |
| 658 |
Find K Closest Elements |
Medium |
| 661 |
Image Smoother |
Easy |
| 662 |
Maximum Width of Binary Tree |
Medium |
| 665 |
Non-decreasing Array |
Easy |
| 669 |
Trim a Binary Search Tree |
Easy |
| 670 |
Maximum Swap |
Medium |
| 671 |
Second Minimum Node In a Binary Tree |
Easy |
| 674 |
Longest Continuous Increasing Subsequence |
Easy |
| 680 |
Valid Palindrome II |
Easy |
| 682 |
Baseball Game |
Easy |
| 686 |
Repeated String Match |
Easy |
| 687 |
Longest Univalue Path |
Easy |
| 693 |
Binary Number with Alternating Bits |
Easy |
| 695 |
Max Area of Island |
Easy |
| 696 |
Count Binary Substrings |
Easy |
| 697 |
Degree of an Array |
Easy |
| 700 |
Search in a Binary Search Tree |
Easy |
| 703 |
Kth Largest Element in a Stream |
Easy |
| 704 |
Binary Search |
Easy |
| 705 |
Design HashSet |
Easy |
| 706 |
Design HashMap |
Easy |
| 707 |
Design Linked List |
Easy |
| 709 |
To Lower Case |
Easy |
| 717 |
1-bit and 2-bit Characters |
Easy |
| 720 |
Longest Word in Dictionary |
Easy |
| 724 |
Find Pivot Index |
Easy |
| 725 |
Split Linked List in Parts |
Medium |
| 728 |
Self Dividing Numbers |
Easy |
| 733 |
Flood Fill |
Easy |
| 734 |
Sentence Similarity |
Easy |
| 737 |
Sentence Similarity II |
Medium |
| 744 |
Find Smallest Letter Greater Than Target |
Easy |
| 746 |
Min Cost Climbing Stairs |
Easy |
| 747 |
Largest Number At Least Twice of Others |
Easy |
| 748 |
Shortest Completing Word |
Easy |
| 760 |
Find Anagram Mappings |
Easy |
| 762 |
Prime Number of Set Bits in Binary Representation |
Easy |
| 766 |
Toeplitz Matrix |
Easy |
| 771 |
Jewels and Stones |
Easy |
| 783 |
Minimum Distance Between BST Nodes |
Easy |
| 784 |
Letter Case Permutation |
Easy |
| 788 |
Rotated Digits |
Easy |
| 804 |
Unique Morse Code Words |
Easy |
| 806 |
Number of Lines To Write String |
Easy |
| 811 |
Subdomain Visit Count |
Easy |
| 812 |
Largest Triangle Area |
Easy |
| 817 |
Linked List Components |
Medium |
| 819 |
Most Common Word |
Easy |
| 821 |
Shortest Distance to a Character |
Easy |
| 824 |
Goat Latin |
Easy |
| 830 |
Positions of Large Groups |
Easy |
| 832 |
Flipping an Image |
Easy |
| 836 |
Rectangle Overlap |
Easy |
| 840 |
Magic Squares In Grid |
Easy |
| 844 |
Backspace String Compare |
Easy |
| 849 |
Maximize Distance to Closest Person |
Easy |
| 852 |
Peak Index in a Mountain Array |
Easy |
| 867 |
Transpose Matrix |
Easy |
| 872 |
Leaf-Similar Trees |
Easy |
| 876 |
Middle of the Linked List |
Easy |
| 883 |
Projection Area of 3D Shapes |
Easy |
| 884 |
Uncommon Words from Two Sentences |
Easy |
| 888 |
Fair Candy Swap |
Easy |
| 892 |
Surface Area of 3D Shapes |
Easy |
| 893 |
Groups of Special-Equivalent Strings |
Easy |
| 896 |
Monotonic Array |
Easy |
| 897 |
Increasing Order Search Tree |
Easy |
| 905 |
Sort Array By Parity |
Easy |
| 908 |
Smallest Range I |
Easy |
| 914 |
X of a Kind in a Deck of Cards |
Easy |
| 917 |
Reverse Only Letters |
Easy |
| 922 |
Sort Array By Parity II |
Easy |
| 925 |
Long Pressed Name |
Easy |
| 929 |
Unique Email Addresses |
Easy |
| 937 |
Reorder Log Files |
Easy |
| 941 |
Valid Mountain Array |
Easy |
| 942 |
DI String Match |
Easy |
| 944 |
Delete Columns to Make Sorted |
Easy |
| 949 |
Largest Time for Given Digits |
Easy |
| 953 |
Verifying an Alien Dictionary |
Easy |
| 961 |
N-Repeated Element in Size 2N Array |
Easy |
| 965 |
Univalued Binary Tree |
Easy |
| 970 |
Powerful Integers |
Easy |
| 973 |
K Closest Points to Origin |
Easy |
| 976 |
Largest Perimeter Triangle |
Easy |
| 977 |
Squares of a Sorted Array |
Easy |
| 984 |
String Without AAA or BBB |
Easy |
| 985 |
Sum of Even Numbers After Queries |
Easy |
| 989 |
Add to Array-Form of Integer |
Easy |
| 993 |
Cousins in Binary Tree |
Easy |
| 994 |
Rotting Oranges |
Easy |
| 997 |
Find the Town Judge |
Easy |
| 999 |
Available Captures for Rook |
Easy |
| 1002 |
Find Common Characters |
Easy |
| 1025 |
Divisor Game |
Easy |
