Design HashSet.cpp

PROBLEM:



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.

Example:

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)

Note:

1. All values will be in the range of [0, 1000000].
2. The number of operations will be in the range of [1, 10000].
3. Please do not use the built-in HashSet library.





class MyHashSet {
    private:
    vector<list<int>> h;
    int size=500;
public:
    /** Initialize your data structure here. */
    MyHashSet() {
        
        h.resize(size);
        
    }
    
    void add(int key) {
        
        int idx=key%size;
        h[idx].push_back(key);
        
    }
    
    void remove(int key) {
        
        int idx=key%size;
        h[idx].remove(key);
        
    }
    
    /** Returns true if this set contains the specified element */
    bool contains(int key) {
        
        int idx=key%size;
        
        for(auto it=h[idx].begin();it!=h[idx].end();it++)
        {
            if(*it==key)
            {
                return true;
            }
        }
        
        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);
 */