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 226-250 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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These are the topics showing up most often in your current queue.

Title	Difficulty	Topics
226. Invert Binary Tree Open source	Easy	TreeDepth-First SearchBreadth-First Search+1 more
227. Basic Calculator II Open source	Medium	MathStringStack
228. Summary Ranges Open source	Easy	Array
229. Majority Element II Open source	Medium	ArrayHash TableSorting+2 more
230. Kth Smallest Element in a BST Open source	Medium	TreeDepth-First SearchBinary Search Tree+1 more
231. Power of Two Open source	Easy	MathBit ManipulationRecursion
232. Implement Queue using Stacks Open source	Easy	StackDesignQueue
233. Number of Digit One Open source	Hard	MathDynamic ProgrammingRecursion
234. Palindrome Linked List Open source	Easy	Linked ListTwo PointersStack+1 more
235. Lowest Common Ancestor of a Binary Search Tree Open source	Medium	TreeDepth-First SearchBinary Search Tree+3 more
236. Lowest Common Ancestor of a Binary Tree Open source	Medium	TreeDepth-First SearchBinary Tree+2 more
237. Delete Node in a Linked List Open source	Medium	Linked List
238. Product of Array Except Self Open source	Medium	ArrayPrefix Sum
239. Sliding Window Maximum Open source	Hard	ArrayQueueSliding Window+3 more
240. Search a 2D Matrix II Open source	Medium	ArrayBinary SearchDivide and Conquer+1 more
241. Different Ways to Add Parentheses Open source	Medium	MathStringDynamic Programming+3 more
242. Valid Anagram Open source	Easy	Hash TableStringSorting
243. Shortest Word Distance Open sourcePremium	Easy	ArrayString
244. Shortest Word Distance II Open sourcePremium	Medium	ArrayHash TableTwo Pointers+2 more
245. Shortest Word Distance III Open sourcePremium	Medium	ArrayString
246. Strobogrammatic Number Open sourcePremium	Easy	Hash TableTwo PointersString
247. Strobogrammatic Number II Open sourcePremium	Medium	ArrayStringRecursion
248. Strobogrammatic Number III Open sourcePremium	Hard	ArrayStringRecursion
249. Group Shifted Strings Open sourcePremium	Medium	ArrayHash TableString
250. Count Univalue Subtrees Open sourcePremium	Medium	TreeDepth-First SearchBinary Tree+1 more