Ranked in these QuestionsQuestion Ranking
Pro Problems faced will force users to practice their algorithm skills
Division 1 upper levels in Topcoder has problems which forces users to think about which is the correct algorithm to use to solve them. A lot of problems will also force developers to use multiple data structures and algorithms to find the solution.
Pro Great community
There are a lot of top programmers who hang around the Topcoder forums answering questions or giving their insight and their way of solving to different problems.