Let's discuss the solutions of all the problems. I am only able to solve A-Small and A-Large. I would like to know other peoples approaches for the other 3 problems. Also how should I prepare for it to get the rank below 300 in the next round.

Here are the problem statements. - Problem A. Sherlock and Parentheses - Problem B. Sherlock and Watson Gym Secrets - Problem C. Watson and Intervals - Problem D. Sherlock and Permutation Sorting