Java: Design HashSet

Difficulty Level: EASY

Problem Statement:

Design and implement a HashSet without using any built-in hash table libraries.

• ‘add(key)’: Insert a value into the HashSet.
• ‘remove(key)’: Remove a value from the HashSet if it exists.
• ‘contains(key)’: Return whether the value exists in the HashSet or not.

Example Usage:

MyHashSet hashSet = new MyHashSet(); 
     hashSet.add(1); 
     hashSet.add(2); 
     hashSet.contains(1);    // returns true 
     hashSet.contains(3);    // returns false (not found) 
     hashSet.add(2); 
     hashSet.contains(2);    // returns true 
     hashSet.remove(2); 
     hashSet.contains(2);    // returns false (already removed)