Codeforces

To avoid plagiarism, encourage learning and logical reasoning, I invite you to read the txt file in each problem, where I explain how I solved it and try to solve it yourself before reviewing any solution. Competitive programming is not just about getting the "accepted" verdict from the virtual judge, but also about learning and improving your logical skills. It's better to spend an extra 30 minutes thinking and solving the problem, than simply having a "solved problem" that you don't even understand.