for example, I have this question https://mirror.codeforces.com/problemset/problem/1692/E which can be easily solved by two pointers, It also contain a tag of binary search, so should I invest my time in thinking about who it will be done with the help of binary search?

please give me some suggestion thanks in advance

currently, I am a newbie and to become a pupil I am practicing 1100 to 1200-rated questions for the last few days, but in the last 2 days I am not able to do even 1000-rated questions I have not able to understand why this happens please give me some suggestions