Why hashmap lookup is O(1) i.e. constant time?

Question

If we look from Java perspective then we can say that hashmap lookup takes constant time. But what about internal implementation? It still would have to search through parti

Answer 1

To follow up on templatetypedef's comments as well:

The constant time implementation of a hash table could be a hashmap, with which you can implement a boolean array list that indicates whether a particular element exists in a bucket. However, if you are implementing a linked list for your hashmap, the worst case would require you going through every bucket and having to traverse through the ends of the lists.