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 126-150 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
126. Word Ladder II Open source	Hard	Hash TableStringBacktracking+2 more
127. Word Ladder Open source	Hard	Hash TableStringBreadth-First Search+1 more
128. Longest Consecutive Sequence Open source	Medium	ArrayHash TableUnion-Find
129. Sum Root to Leaf Numbers Open source	Medium	TreeDepth-First SearchBinary Tree
130. Surrounded Regions Open source	Medium	ArrayDepth-First SearchBreadth-First Search+2 more
131. Palindrome Partitioning Open source	Medium	StringDynamic ProgrammingBacktracking
132. Palindrome Partitioning II Open source	Hard	StringDynamic Programming
133. Clone Graph Open source	Medium	Hash TableDepth-First SearchBreadth-First Search+1 more
134. Gas Station Open source	Medium	ArrayGreedy
135. Candy Open source	Hard	ArrayGreedy
136. Single Number Open source	Easy	ArrayBit Manipulation
137. Single Number II Open source	Medium	ArrayBit Manipulation
138. Copy List with Random Pointer Open source	Medium	Hash TableLinked List
139. Word Break Open source	Medium	ArrayHash TableString+4 more
140. Word Break II Open source	Hard	ArrayHash TableString+4 more
141. Linked List Cycle Open source	Easy	Hash TableLinked ListTwo Pointers+1 more
142. Linked List Cycle II Open source	Medium	Hash TableLinked ListTwo Pointers+1 more
143. Reorder List Open source	Medium	Linked ListTwo PointersStack+1 more
144. Binary Tree Preorder Traversal Open source	Easy	StackTreeDepth-First Search+1 more
145. Binary Tree Postorder Traversal Open source	Easy	StackTreeDepth-First Search+1 more
146. LRU Cache Open source	Medium	Hash TableLinked ListDesign+1 more
147. Insertion Sort List Open source	Medium	Linked ListSorting
148. Sort List Open source	Medium	Linked ListTwo PointersDivide and Conquer+2 more
149. Max Points on a Line Open source	Hard	ArrayHash TableMath+3 more
150. Evaluate Reverse Polish Notation Open source	Medium	ArrayMathStack