Hashing

Hashing is one of the most important techniques used in DSA to quickly store and retrieve information. It commonly uses data structures such as HashMap and HashSet to keep track of values, counts, indexes, or previously seen elements. Hashing is extremely useful for problems involving frequency counting, duplicate detection, finding pairs, grouping values, and fast lookups. Many brute-force problems can be optimized significantly by using hashing. In this section, you’ll learn how to identify problems where HashMap or HashSet can make the solution simpler and faster.