Many times, my submission end up failing some test case, and I am left bemused as to what was wrong with it. In such cases, I ask people in the editorial, but that cannot be done for past problems.

I know I can understand the solution from the editorial, but I also want to know what was wrong with my approach (this is especially true when my approach is more or less the same). What should I do?

Lately, I have been experiencing trouble logging in to Codeforces. When I clicked on log in via Gmail, it gave a message saying "Access blocked: This app's request is invalid". This problem was first encountered on March 30. The next day, I retried. This time around, Codeforces asked me to change my Gmail account's password. I don't know why I was asked to do so, but I obliged and the problem went away.

This past Friday, the problem returned! And this time around, it won't go away. Even changing the password (this time I wasn't prompted by Codeforces to do so) didn't yield any results. Since then, this is my first time logging in successfully. Why is this happening? And how can I avoid this? How do I contact Codeforces' support team if this issue rears its ugly head again? Please help!

Note that I have never violated any of Codeforces' rules and regulations such as sharing solutions, asking for solutions, being rude to community members etc.