705. Design HashSet

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

Implement MyHashSet class:

• void add(key) Inserts the value key into the HashSet.
• bool contains(key) Returns whether the value key exists in the HashSet or not.
• void remove(key) Removes the value key in the HashSet. If key does not exist in the HashSet, do nothing.

计算哈希值，使用数组实现Hash Set。

class MyHashSet {
    int PRIME = 1009;
    List<Integer>[] data;
    
    public MyHashSet() {
        data = new List[PRIME];
        for(int i = 0; i < PRIME; i++){
            data[i] = new LinkedList<Integer>();
        }
    }
    
    public void add(int key) {
        if(!contains(key)){
            int h = getHash(key);
            data[h].add(key);
        }
    }
    
    public void remove(int key) {
        int h = getHash(key);
        data[h].remove(new Integer(key));
    }
    
    public boolean contains(int key) {
        int h = getHash(key);
        for( int num : data[h] ){
            if( num == key ){
                return true;
            }
        }
        return false;
    }
    
    private int getHash(int o){
        return o % PRIME;
    }
}

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