List of sites for cp
1. Codeforces
2. CodeChef
3. HackerRank
4. LeetCode
5. TopCoder
6. AtCoder
7. UVa Online Judge
8. SPOJ
9. Project Euler
10. ACM-ICPC Live Archive
11. Timus Online Judge
12. USACO
13. HackerEarth
14. A2 Online Judge
15. Kattis
16. GeeksforGeeks
17. InterviewBit
18. HackerRank for Work
19. CodeSignal
20. Codewars