Hi,
Drop some of your favorite problems which you think can educate us some new concept, tricks or ideas and we have a take away from those problems. :)
Please try to follow this particular format so that it is helpful for the readers (and also to me):

Probelm Rating (Eg: 1500) :
- Problem 1 (Why you recommend this problem)
- Problem 2 (Why you recommend this problem)
Probelm Rating 2 (Eg: 1600) :
- Problem 1 (Why you recommend this problem)
- Problem 2 (Why you recommend this problem)

You can also drop problems without following this xD. Just don't forget to drop some cool problems which we should definitely practice. :)

So, I have encountered a strange problem while solving 1541B — Pleasent Pairs
My first solution gets accepted ( Solution 1 ) , while the second one got TLE ( Solution 2).

I don't understand why this is happening. They both are almost same. Any help?
Thank you.

Hello everyone,
I want to reach Expert within an year. I can solve codeforces A,B problems mostly. Sometimes (very rarely) I manage to solve C. I want to practice Codeforces and want to reach till Expert. Should I practice from USACO? If yes, how should I practice?

Also other tips that would be helpful to reach expert are welcome.
Thank You.