영어
- Topcoder
- Google Codejam
- HackerRank
- Codeforces
- sponsered by Telegram
- Scala 지원 2.11.1 2015.10.7 기준
- Codechef
- Codewars
- Peking Univ. Judge Online
- Sphere Online Judge
한국어
Reference
- 곽중선님 블로그 : 알고리즘 학습 전반에 대해 잘 정리되어있습니다.
- Quora:How good is the quality of HackerRank problems compared to problems of Topcoder, Codeforces, Codechef?