I haven't but I will check it out! From my time at /r/cscareerquestions, LeetCode is the "hardest" and thus the best for top companies. HackerRank is good but

I haven't but I will check it out! From my time at /r/cscareerquestions, LeetCode is the "hardest" and thus the best for top companies. HackerRank is good but every challenge requires parsing STDIN instead of just giving arguments to a function the user writes. It's very annoying to me and a deal breaker, especially with certain languages.