https://leetcode.com/problems/design-hashset/description/

class MyHashSet {
public:
    int Set[1000010] = {0};
    /** Initialize your data structure here. */
    MyHashSet() {
        
    }
    
    void add(int key) {
        if(Set[key]==0) Set[key]+=1;
    }
    
    void remove(int key) {
        if(Set[key]>0) Set[key] = 0;
    }
    
    /** Returns true if this set contains the specified element */
    bool contains(int key) {
        if(Set[key]>0) 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);
 */