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Questions by Topic

Practice problems organized by data structure and algorithm topics to focus your learning.

Data Structures

Linked List

3 questions

Master pointer manipulation and list traversal.

Reverse a Linked List Add Two Numbers Merge Two Sorted Lists

Strings

4 questions

Practice essential string manipulation patterns.

Merge Strings Alternately Longest Substring Without Repeating Characters Valid Anagram Length of Last Word

Trees

2 questions

Explore hierarchical data structures and recursion.

Binary Tree Inorder Traversal Maximum Depth of Binary Tree

Arrays

5 questions

Master array manipulation and indexing techniques.

Two Sum Best Time to Buy and Sell Stock Merge Intervals Contains Duplicate Remove Element

Stacks & Queues

1 question

Learn LIFO and FIFO data structures.

Valid Parentheses

Hash Tables

2 questions

Master key-value pair storage and lookup.

Two Sum Contains Duplicate

Heaps

Coming Soon

Learn priority queues and heap operations.

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Math

1 question

Master modular arithmetic and number manipulation.

Palindrome Number

Algorithms

Dynamic Programming

1 problem

Solve complex problems by breaking them down.

Climbing Stairs

Linear Search

Coming Soon

Scan through elements to find a match.

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Visual linear search guide coming soon!

Sorting Algorithms

Coming Soon

Visual comparisons: quicksort vs merge sort and more.

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Sorting animations coming soon!

Binary Tree Traversal

Coming Soon

Inorder, preorder, postorder traversals visualized.

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Traversal animations coming soon!

Two Pointers

2 questions

Efficiently solve problems with two moving pointers.

Best Time to Buy and Sell Stock Remove Element

Sliding Window

1 question

Optimize problems with a moving window approach.

Longest Substring Without Repeating Characters

Binary Search

1 question

Efficiently search in sorted data structures.

Binary Search

Easy

Search sorted array by repeatedly dividing search space in half.

Graph Algorithms

Coming Soon

Master BFS, DFS, and graph traversal techniques.

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Greedy

Coming Soon

Make locally optimal choices for global optimization.

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