Problem Library

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

All tracks Blind 75 NeetCode 150 NeetCode 250 Striver A to Z SDE Sheet

Showing 101-125 of 250 matching problems.

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All topics Algorithm X Array Backtracking Bidirectional Search Binary Indexed Tree Binary Lifting Binary Search Binary Search Tree Binary Tree Bit Manipulation Boyer–Moore Majority Vote Algorithm Boyer–Moore String-Search Algorithm Bracket Sequences Breadth-First Search Brute-Force Search Bubble Sort Bucket Sort Combinatorics

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Title	Difficulty	Topics
101. Symmetric Tree Open source	Easy	TreeDepth-First SearchBreadth-First Search+1 more
102. Binary Tree Level Order Traversal Open source	Medium	TreeBreadth-First SearchBinary Tree
103. Binary Tree Zigzag Level Order Traversal Open source	Medium	TreeBreadth-First SearchBinary Tree
104. Maximum Depth of Binary Tree Open source	Easy	TreeDepth-First SearchBreadth-First Search+1 more
105. Construct Binary Tree from Preorder and Inorder Traversal Open source	Medium	ArrayHash TableDivide and Conquer+2 more
106. Construct Binary Tree from Inorder and Postorder Traversal Open source	Medium	ArrayHash TableDivide and Conquer+2 more
107. Binary Tree Level Order Traversal II Open source	Medium	TreeBreadth-First SearchBinary Tree
108. Convert Sorted Array to Binary Search Tree Open source	Easy	ArrayDivide and ConquerTree+2 more
109. Convert Sorted List to Binary Search Tree Open source	Medium	Linked ListDivide and ConquerTree+2 more
110. Balanced Binary Tree Open source	Easy	TreeDepth-First SearchBinary Tree
111. Minimum Depth of Binary Tree Open source	Easy	TreeDepth-First SearchBreadth-First Search+1 more
112. Path Sum Open source	Easy	TreeDepth-First SearchBreadth-First Search+1 more
113. Path Sum II Open source	Medium	BacktrackingTreeDepth-First Search+1 more
114. Flatten Binary Tree to Linked List Open source	Medium	Linked ListStackTree+2 more
115. Distinct Subsequences Open source	Hard	StringDynamic Programming
116. Populating Next Right Pointers in Each Node Open source	Medium	Linked ListTreeDepth-First Search+2 more
117. Populating Next Right Pointers in Each Node II Open source	Medium	Linked ListTreeDepth-First Search+2 more
118. Pascal's Triangle Open source	Easy	ArrayDynamic Programming
119. Pascal's Triangle II Open source	Easy	ArrayDynamic Programming
120. Triangle Open source	Medium	ArrayDynamic Programming
121. Best Time to Buy and Sell Stock Open source	Easy	ArrayDynamic Programming
122. Best Time to Buy and Sell Stock II Open source	Medium	ArrayDynamic ProgrammingGreedy
123. Best Time to Buy and Sell Stock III Open source	Hard	ArrayDynamic Programming
124. Binary Tree Maximum Path Sum Open source	Hard	Dynamic ProgrammingTreeDepth-First Search+2 more
125. Valid Palindrome Open source	Easy	Two PointersString