Problem Library

Master these coding challenges to ace your next technical interview. Handpicked problems with personalized spaced repetition.

Showing 11 of 66 problems in NeetCode 150.

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Array36Dynamic Programming15Depth-First Search14

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Title	Difficulty	Topics
98. Validate Binary Search Tree	Medium	TreeDepth-First SearchBinary Search Tree+1 more
100. Same Tree	Easy	TreeDepth-First SearchBreadth-First Search+1 more
102. Binary Tree Level Order Traversal	Medium	TreeBreadth-First SearchBinary Tree
104. Maximum Depth of Binary Tree	Easy	TreeDepth-First SearchBreadth-First Search+1 more
105. Construct Binary Tree from Preorder and Inorder Traversal	Medium	ArrayHash TableDivide and Conquer+2 more
110. Balanced Binary Tree	Easy	TreeDepth-First SearchBinary Tree
199. Binary Tree Right Side View	Medium	TreeDepth-First SearchBreadth-First Search+1 more
226. Invert Binary Tree	Easy	TreeDepth-First SearchBreadth-First Search+1 more
230. Kth Smallest Element in a BST	Medium	TreeDepth-First SearchBinary Search Tree+1 more
235. Lowest Common Ancestor of a Binary Search Tree	Medium	TreeDepth-First SearchBinary Search Tree+1 more
236. Lowest Common Ancestor of a Binary Tree	Medium	TreeDepth-First SearchBinary Tree