101 |
Symmetric Tree |
Easy |
Tree
|
Depth-first Search
|
Breadth-first Search
|
102 |
Binary Tree Level Order Traversal |
Medium |
Tree
|
Breadth-first Search
|
103 |
Binary Tree Zigzag Level Order Traversal |
Medium |
Stack |
Tree
|
Breadth-first Search
|
104 |
Maximum Depth of Binary Tree |
Easy |
Tree
|
Depth-first Search
|
105 |
Construct Binary Tree from Preorder and Inorder Traversal |
Medium |
Array
|
Tree
|
Depth-first Search
|
106 |
Construct Binary Tree from Inorder and Postorder Traversal |
Medium |
Array
|
Tree
|
Depth-first Search
|
107 |
Binary Tree Level Order Traversal II |
Medium |
Tree
|
Breadth-first Search
|
108 |
Convert Sorted Array to Binary Search Tree |
Easy |
Tree
|
Depth-first Search
|
110 |
Balanced Binary Tree |
Easy |
Tree
|
Depth-first Search
|
111 |
Minimum Depth of Binary Tree |
Easy |
Tree
|
Depth-first Search Breadth-first Search
|
112 |
Path Sum |
Easy |
Tree
|
Depth-first Search
|
113 |
Path Sum II |
Medium |
Tree
|
Depth-first Search
|
114 |
Flatten Binary Tree to Linked List |
Medium |
Tree
|
Depth-first Search
|
116 |
Populating Next Right Pointers in Each Node |
Medium |
Tree
|
Depth-first Search
|
117 |
Populating Next Right Pointers in Each Node II |
Medium |
Tree
|
Depth-first Search
|
118 |
Pascal's Triangle |
Easy |
Array
|
119 |
Pascal's Triangle II |
Easy |
Array
|
120 |
Triangle |
Medium |
Array
|
Dynamic Programming
|
121 |
Best Time to Buy and Sell Stock |
Easy |
Array
|
Dynamic Programming
|
122 |
Best Time to Buy and Sell Stock II |
Easy |
Array
|
Greedy
|
123 |
Best Time to Buy and Sell Stock III |
Hard |
Array
|
Dynamic Programming
|
124 |
Binary Tree Maximum Path Sum |
Hard |
Tree
|
Depth-first Search
|
126 |
Word Ladder II |
Hard |
Array
|
String
|
Backtracking |
Breadth-first Search
|
129 |
Sum Root to Leaf Numbers |
Medium |
Tree
|
Depth-first Search
|
130 |
Surrounded Regions |
Medium |
Depth-first Search
|
Breadth-first Search
|
Union Find
|
141 |
Linked List Cycle |
Easy |
|
142 |
Linked List Cycle II |
Medium |
|
143 |
Reorder List |
Medium |
|
144 |
Binary Tree Preorder Traversal |
Medium |
Stack |
Tree
|
145 |
Binary Tree Postorder Traversal |
Medium |
Tree
|
Stack
|
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 |
Array
|
Dynamic Programming
|
153 |
Find Minimum in Rotated Sorted Array |
Medium |
|
154 |
Find Minimum in Rotated Sorted Array II |
Hard |
|
155 |
Min Stack |
Easy |
|
156 |
Binary Tree Upside Down |
Medium |
Tree
|
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 |
Stack |
Tree
|
Design
|
174 |
Dungeon Game |
Hard |
|
176 |
Second Highest Salary |
Easy |
|
179 |
Largest Number |
Medium |
|
188 |
Best Time to Buy and Sell Stock IV |
Hard |
|
189 |
Rotate Array |
Medium |
|
190 |
Reverse Bits |
Easy |
|
191 |
Number of 1 Bits |
Easy |
|
198 |
House Robber |
Medium |
|
199 |
Binary Tree Right Side View |
Medium |
Tree
|
Depth-first Search
|
Breadth-first Search
|
200 |
Number of Islands |
Medium |
|