- Basics and STL
- Greedy, Divide and Conquer, Binary Search
- Dynamic Programming
- Maths for programming contests
- Graph Theory
- Segment Trees

Problem Classifier -I

Problem Classifier - II

For any problem click on "Best Solutions", it shows the number of users who have successfully solved it. This is a good way to decide how easy or tough a problem is, unless it is a very recently added one.