Competitive Programming Essentials -

Segment Trees and Fenwick Trees (Binary Indexed Trees) for range queries. Hashing: Using Hash Maps for average-time lookups. 3. Core Algorithmic Paradigms

Most problems fall into specific patterns of logic. Recognizing these is half the battle. Sorting and Searching competitive programming essentials

This is the most important habit. After a contest, solve the problems you missed. Segment Trees and Fenwick Trees (Binary Indexed Trees)