- http://codeforces.com/problemset/problem/628/F
- http://codeforces.com/gym/100729 : Problem F
- http://codeforces.com/gym/100517 : Problem H
- http://codeforces.com/gym/101128 : Problem F
- http://codeforces.com/gym/100491 : Problem A
- http://codeforces.com/gym/101175 : Problem D (WF)
- http://codeforces.com/gym/101221 : Problem I (WF)
- http://codeforces.com/gym/100800 : Problem A
- http://codeforces.com/gym/101239 : Problem C (WF)
- http://codeforces.com/gym/101208 : Problem C (WF)
- http://codeforces.com/contest/717/problem/G
- https://www.hackerearth.com/challenge/test/indiahacks-algorithm-finals/approximate/8dfacb488e7d47b9856993bd9593932e/ : Really Nice problem.
- Link to easier version : http://codeforces.com/contest/653/problem/D (The editorial on CF has explanation of the original problem)
- https://www.codechef.com/problems/CHN16E : Another really nice problem!
- http://codeforces.com/gym/101173 : Problem B
- http://codeforces.com/gym/100827 : Problem C
credits: Tanuj Khattar