I want to invite you to participate in HackerEarth May Clash '15. It is 24h-long contest, scheduled on May, 23 (check your timezone). Problemset consists of 5 algorithmic tasks of varying difficulty with partial solutions allowed - you get points for every test that you solution passed, and one approximate problem - your score for this task depends on how good your solution is comparing to current best solution.
There will be nice prizes for toppers:
Amazon Gift Cards for top3 ($80 - 60 - 40)
HackerEarth T-shirts for top5.
Upd. First announcement said that contest is scheduled on May, 16. Due to unavoidable reasons it has been moved on May, 23 now.