Hash Table practice problems

A focused problem list tied to the real-world applications on this topic. Open any problem directly on its platform.

4 problems List view Mobile optimized

Why this page exists

The main topic page explains where the idea is used in production. This child page is only for practice.

Hash Table practice

4 items

Two Sum

The standard exact-key lookup problem for hash maps.

Valid Anagram

Frequency counting with a simple key-to-count map.

Group Anagrams

Canonical-key grouping built on hash table lookup.

Design HashMap

Closer to the data structure itself instead of just using a built-in map.