| 0001 |
Two Sum |
Easy |
array; lookup table |
| 0002 |
Add Two Numbers |
Medium |
linked list |
| 0003 |
Longest Substring Without Repeating Characters |
Medium |
sliding window |
| 0004 |
4. Median of Two Sorted Arrays |
Hard |
binary search |
| 0007 |
7. Reverse Integer |
Easy |
math |
| 0009 |
9. Palindrome Number |
Easy |
math |
| 0011 |
11. Container With Most Water |
Medium |
array; double index |
| 0013 |
13. Roman to Integer |
Easy |
math |
| 0014 |
14. Longest Common Prefix |
Easy |
|
| 0015 |
15. 3Sum |
Medium |
|
| 0017 |
Letter Combinations of a Phone Number |
Medium |
tree |
| 0019 |
19. Remove Nth Node From End of List |
Medium |
linked list |
| 0020 |
Valid Parentheses |
Easy |
string; stack |
| 0021 |
Merge Two Sorted Lists |
Easy |
linked list |
| 0023 |
23. Merge k Sorted Lists |
Hard |
linked list; heap |
| 0024 |
24. Swap Nodes in Pairs |
Medium |
linked list |
| 0025 |
Reverse Nodes in k-Group |
Hard |
linked list |
| 0026 |
Remove Duplicates from Sorted Array |
Easy |
array; double index |
| 0027 |
Remove Element |
Easy |
array |
| 0028 |
28. Implement strStr() |
Easy |
double index |
| 0033 |
Search in Rotated Sorted Array |
Medium |
binary search |
| 0034 |
Find First and Last Position of Element in Sorted Array |
Medium |
binary search |
| 0035 |
35. Search Insert Position |
Easy |
binary search |
| 0048 |
48. Rotate Image |
Medium |
array |
| 0053 |
53. Maximum Subarray |
Easy |
dynamic programming |
| 0058 |
58. Length of Last Word |
Easy |
|
| 0061 |
Rotate List |
Medium |
linked list |
| 0062 |
Unique Paths |
Medium |
recursion; memory search; dynamic programming |
| 0063 |
Unique Paths 2 |
Medium |
recursion; memory search; dynamic programming |
| 0064 |
Minimum Path Sum |
Medium |
dynamic programming; dfs |
| 0066 |
66. Plus One |
Easy |
math |
| 0067 |
add Binary |
Easy |
|
| 0069 |
Sqrt(x) |
Easy |
binary search |
| 0070 |
Climbing Stairs |
Easy |
dynamic programming |
| 0075 |
75. Sort Colors |
Medium |
sort |
| 0076 |
Minimum Window Substring |
Hard |
sliding window |
| 0077 |
77. Combinations |
Medium |
backtracking; combine |
| 0079 |
79. Word Search |
Medium |
backtracking; array |
| 0080 |
80. Remove Duplicates from Sorted Array II |
Medium |
double index |
| 0082 |
82. Remove Duplicates from Sorted List II |
Medium |
linked list |
| 0083 |
83. Remove Duplicates from Sorted List |
Easy |
linked list |
| 0086 |
86. Partition List |
Medium |
linked list |
| 0088 |
88. Merge Sorted Array |
Easy |
sort |
| 0092 |
92. Reverse Linked List II |
Medium |
linked list |
| 0094 |
Binary Tree Inorder Traversal |
Medium |
binary tree |
| 0100 |
Same Tree |
Easy |
binary tree |
| 0101 |
Symmetric Tree |
Easy |
stack; recursion; iterative |
| 0102 |
102. Binary Tree Level Order Traversal |
Medium |
binary tree; bfs |
| 0104 |
104. Maximum Depth of Binary Tree |
Easy |
binary tree |
| 0107 |
Binary Tree Level Order Traversal II |
Easy |
binary tree |
| 0111 |
Minimum Depth of Binary Tree |
Easy |
binary tree |
| 0112 |
Path Sum |
Easy |
binary tree |
| 0120 |
Triangle |
Medium |
dynamic programming; dfs |
| 0121 |
121. Best Time to Buy and Sell Stock |
Easy |
|
| 0122 |
122. Best Time to Buy and Sell Stock II |
Easy |
greedy |
| 0125 |
Valid Palindrome |
Easy |
|
| 0136 |
136. Single Number |
Easy |
hash table; bit manipulation |
| 0144 |
144. Binary Tree Preorder Traversal |
Medium |
binary tree |
| 0148 |
148. Sort List |
Medium |
sort; linked list |
| 0150 |
150. Evaluate Reverse Polish Notation |
Medium |
stack |
| 0153 |
153. Find Minimum in Rotated Sorted Array |
Medium |
binary search |
| 0155 |
155. Min Stack |
Easy |
stack |
| 0165 |
165. Compare Version Numbers |
Medium |
string |
| 0167 |
Two Sum II - Input array is sorted |
Easy |
ε―Ήζζι(εη΄’εΌ) |
| 0179 |
179. Largest Number |
Medium |
sort |
| 0198 |
House Robber |
Easy |
memory search; dynamic programming |
| 0200 |
200. Number of Islands |
Medium |
dfs; bfs |
| 0203 |
203. Remove Linked List Elements |
Easy |
linked list |
| 0206 |
206. Reverse Linked List |
Easy |
linked list |
| 0208 |
208. Implement Trie (Prefix Tree) |
Medium |
trie |
| 0209 |
Minimum Size Subarray Sum |
Medium |
sliding window |
| 0211 |
211. Add and Search Word - Data structure design |
Medium |
trie |
| 0215 |
215. Kth Largest Element in an Array |
Medium |
sort |
| 0217 |
217. Contains Duplicate |
Easy |
map |
| 0219 |
219. Contains Duplicate II |
Easy |
map |
| 0226 |
Invert Binary Tree |
Easy |
recursion; binary tree |
| 0235 |
235. Lowest Common Ancestor of a Binary Search Tree |
Easy |
recursion; binary tree |
| 0236 |
236. Lowest Common Ancestor of a Binary Tree |
Medium |
recursion; binary tree |
| 0237 |
237. Delete Node in a Linked List |
Easy |
linked list |
| 0257 |
257. Binary Tree Paths |
Easy |
binary tree |
| 0258 |
258. Add Digits |
Easy |
math |
| 0283 |
Move Zeroes(solution1) Move Zeroes(solution2) |
Easy |
array |
| 0300 |
Longest Increasing Subsequence |
Medium |
dp |
| 0303 |
303. Range Sum Query - Immutable |
Easy |
|
| 0304 |
304. Range Sum Query 2D - Immutable |
Medium |
dp |
| 0307 |
307. Range Sum Query - Mutable |
Medium |
segment tree |
| 0328 |
328. Odd Even Linked List |
Medium |
singly linked list |
| 0343 |
Integer Break |
Medium |
recursion; memory search; dynamic programming |
| 0344 |
344. Reverse String |
Easy |
double index |
| 0345 |
345. Reverse Vowels of a String |
Easy |
double index |
| 0347 |
347. Top K Frequent Elements |
Medium |
map; heap; array |
| 0349 |
Intersection of Two Arrays |
Easy |
set |
| 0350 |
Intersection of Two Arrays II |
Easy |
map |
| 0376 |
Wiggle Subsequence |
Medium |
dp |
| 0392 |
Is Subsequence |
Medium |
greedy algorithm |
| 0404 |
404. Sum of Left Leaves |
Easy |
binary tree |
| 0416 |
Partition Equal Subset Sum |
Medium |
dp; 0-1 knapsack problem |
| 0435 |
Non-overlapping Intervals(dp solution) Non-overlapping Intervals(greedy solution) |
Medium |
dp; 0-1 knapsack problem |
| 0437 |
437. Path Sum III |
Easy |
binary tree |
| 0438 |
Find All Anagrams in a String |
Easy |
sliding window |
| 0447 |
Number of Boomerangs |
Easy |
|
| 0454 |
4Sum II |
Medium |
|
| 0455 |
Assign Cookies |
Easy |
greedy algorithm |
| 0557 |
557. Reverse Words in a String III |
Easy |
string |
| 0674 |
674. Longest Continuous Increasing Subsequence |
Easy |
|
| 0677 |
677. Map Sum Pairs |
Medium |
trie |
| 0704 |
Binary Search |
Easy |
binary search |
| 0713 |
713. Subarray Product Less Than K |
Medium |
sliding window |
| 0717 |
717. 1-bit and 2-bit Characters |
Easy |
|
| 0728 |
Self Dividing Numbers |
Easy |
|
| 0735 |
735. Asteroid Collision |
Medium |
stack |
| 0747 |
Largest Number At Least Twice of Others |
Easy |
|
| 0872 |
872. Leaf-Similar Trees |
Easy |
binary tree |
| 1021 |
1021. Remove Outermost Parentheses |
Easy |
stack |