Those problems are certainly interesting to learn a language and to learn algorithms, but almost all contests I tried have one MAJOR MAJOR problem, which is why

Those problems are certainly interesting to learn a language and to learn algorithms, but almost all contests I tried have one MAJOR MAJOR problem, which is why I stopped solving those interesting problems: It is like trying to fix a complicated robot which should work perfectly by my confidence in total darkness, wearing oven mitts without tools. Yes, once you submit, you get back WRONG. You question your algorithm, you question your understanding of the problem, you question yourself, you question the forum, but there is no error. Great. So you can just stop trying to solve the problem and do something else and probably assume that either the problem description is wrong or the input/output is wrong. This is certainly not fun at all.