Codeforces (codeforces.com) is a website for competitive programmers. It provides following services:
• participation in the short (2-hours) contests, held about once a week
• hacking other contestants solutions
• participation in past contests, such as ACM ICPC NEERC
• ability to solve problems from previous contests for training purposes
This app can:
• show your rating
• show list of past & future contests
• create calendar events when round starts