LeetCode

LeetCode is the premier online platform for software engineers to practice coding problems, master algorithms, and prepare for technical interviews at top-tier tech companies.

This platform provides a massive repository of over 4050 coding problems, focusing on critical data structures and algorithms (DSA) concepts. Users solve these problems in an in-browser environment supporting 14 popular languages (e.g., Python, Java, C++), with solutions evaluated on execution speed and memory usage. LeetCode supports focused interview preparation through features like mock interviews, daily challenges, and a filter to practice company-specific questions. The active community forum is key: it allows users to share solutions, discuss complexity (Big O Notation), and collaborate on problem-solving techniques.

https://leetcode.com/