HackerRank is a great place for training, and is very good for interview. Imho it's better than using a google doc. Anyway they organize a lot of contests, and

HackerRank is a great place for training, and is very good for interview. Imho it's better than using a google doc. Anyway they organize a lot of contests, and saying "Beware of HackerRank" is not correct, it should rather be "I participated one time on HackerRank and I didn't like it".