c++ \hashmap

A hashmap is a data structure that allows for efficient storage and retrieval of key-value pairs. It uses a hashing function to map each key to a bucket in an array, where the value is stored. This allows for constant-time (O(1)) access to values based on their key, making it useful for applications such as caching, indexing, and database systems. However, hashmaps can have collision issues if two keys map to the same bucket, which can be resolved through techniques such as chaining or open addressing.