Hash map is a widely used efficient data structure that used to store data which can be searched in constant time O(1). It is also referred as hash table, unordered map, dictionary, hash set and others. This data structure is implemented over an array that maps keys to values. Hence, hash map can be seen as a **set of key value pairs**. Each key is a number in the range of 0 to the array size – 1, generated by a **hash function**.

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