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

Design HashSet

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

To be specific, your design should include these functions:

• add(value): Insert a value into the HashSet. 
• contains(value) : Return whether the value exists in the HashSet or not.
• remove(value): Remove a value in the HashSet. If the value does not exist in the HashSet, do nothing.

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)

class MyHashSet {
public:
    /** Initialize your data structure here. */
    unordered_map<int,int> mp;
    MyHashSet() {
     // unordered_map<int,int> mp;
    }
   
    void add(int key) {
        mp[key]=1;
    }
   
    void remove(int key) {
      mp.erase(key);
    }
   
    /** Returns true if this set contains the specified element */
    bool contains(int key) {
        if(mp[key]==1)
            return true;
            else
                return false;
    }
};

/**
 * Your MyHashSet object will be instantiated and called as such:
 * MyHashSet* obj = new MyHashSet();
 * obj->add(key);
 * obj->remove(key);
 * bool param_3 = obj->contains(key);
 */