It would be nice if people who have solved the problems could add some hints to the problems they have solved. You can find samples of hints in the Competitive Programming community.

Problems are hosted on Kattis

1. Balanced Diet
2. Branch Assignment
3. Ceiling Function
4. Clock Breaking
5. Forever Young
6. Longest Rivers
7. Oil
8. Polygonal Puzzle
9. Road Times
10. Spin Doctor
11. String Theory
12. Swap Space
13. What Really Happened on Mars?