@nikmul19 - I will suggest to follow a plan. No use doing ahead topics until the fundamental and basic ones are clear. Eg - If data structures like stack, queue, maps and vectors arent clear you will have problem in graph and some DP problems.
@pyhooma - Honestly, nothing particular. I think CCDSAP prepare section has extensive resources for it. All I did in my time was just learning what the data structure does, its applications and some basic practice problems. For rest of topics I searched for problems via tags.
@rahul127 - The topics for last few problems of div2 are much wider and tougher. Mostly, you should try to have a grasp on-
- Graph algorithms. BFS, DFS, shortest paths, directed graph algorithms (Toposort etc) are a must.
- DP problems upto easy-medium or medium difficulty.
- Tries. Have an idea of what they are so you can identify if the problem requires it.
- Sometimes math comes. Not much can be recommended here. But a book called “Concrete Mathematics” is very nice to get idea of competitive coding maths.
- Data structures like DSU, Seg tree.
- Tricks like Difference Array, Square root decomposition.
- Graph algos again! Many times graph algos are used in combination of above data structures. Eg- Euler Tour + Difference Array etc.
If you look at problems of August long this year, the distribution was as follows-
- KS1 - Adhoc, math to come up with formulas, properties of XOR
- ENCODING- Digit DP (easy-med or med level dp)
- CHGORAM - Euler Tour, Segment Tree, DFS