Hash Set and Hash Table
The Principle of Built-in Hash Table The key value can be any hashable type. A value that belongs to a hashable type has a hash code, and this code is used to get the bucket index. Each bucket contains an array to store all the values in the same bucket initially If there are too many values in the bucket, these values will be stored in the form of height-balanced BST so that look-up can be more efficient.