LeetCode

• Why to Use: LeetCode offers a vast array of problems categorized by difficulty level and topic, with the ability to run your code against multiple test cases. It's great for improving coding skills and preparing for interviews.
• LeetCode

HackerRank

• Why to Use: HackerRank provides a wide range of DSA problems along with contests and challenges to improve coding skills. It's popular for its practical coding challenges and interview preparation resources.
• HackerRank

CodeSignal

• Why to Use: CodeSignal offers a platform for DSA practice, as well as interview preparation with real-world questions. It's known for its comprehensive approach to coding assessments and skill improvement.
• CodeSignal

GeeksforGeeks

• Why to Use: GeeksforGeeks is known for its vast collection of DSA tutorials and articles. It also offers a practice section with a wide range of problems for hands-on practice. It's a comprehensive resource for learning and practicing DSA.
• GeeksforGeeks

CodeChef

• Why to Use: CodeChef provides monthly coding contests along with a practice section for DSA and competitive programming. It's popular for its challenging contests and strong community of competitive programmers.
• CodeChef

TopCoder

• Why to Use: TopCoder offers algorithmic challenges and contests for practicing DSA. It's known for its challenging problems and competitive environment, making it a great platform for experienced programmers.
• TopCoder

Project Euler

• Why to Use: Project Euler focuses on mathematical and computational problems that require the use of DSA concepts. It's popular among math enthusiasts and programmers looking for intellectually stimulating challenges.
• Project Euler

Interviewbit

• Why to Use: Interviewbit provides a curated set of DSA problems specifically tailored for interview preparation. It's a great resource for job seekers looking to ace technical interviews.
• Interviewbit

Spoj (Sphere Online Judge)

• Why to Use: Spoj offers a collection of algorithmic problems to solve online, with a focus on competitive programming. It's popular among competitive programmers for its extensive problem archive and challenging problems.
• Spoj

AtCoder

• Why to Use: AtCoder is a platform for practicing competitive programming with regular contests and a large problem archive. It's popular for its well-organized contests and high-quality problems.
• AtCoder