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.

Example 1:

Input
["MyHashSet", "add", "add", "contains", "contains", "add", "contains", "remove", "contains"]
[[], [1], [2], [1], [3], [2], [2], [2], [2]]

Output
[null, null, null, true, false, null, true, null, false]

Explanation

MyHashSet myHashSet = new MyHashSet();
myHashSet.add(1);      // set = [1]
myHashSet.add(2);      // set = [1, 2]
myHashSet.contains(1); // return True
myHashSet.contains(3); // return False, (not found)
myHashSet.add(2);      // set = [1, 2]
myHashSet.contains(2); // return True
myHashSet.remove(2);   // set = [1]
myHashSet.contains(2); // return False, (already removed)

풀이

var MyHashSet = function() {
    this.set = {};
};

/** 
 * @param {number} key
 * @return {void}
 */
MyHashSet.prototype.add = function(key) {
    this.set[key] = true;
};

/** 
 * @param {number} key
 * @return {void}
 */
MyHashSet.prototype.remove = function(key) {
    delete this.set[key];
};

/** 
 * @param {number} key
 * @return {boolean}
 */
MyHashSet.prototype.contains = function(key) {
    return this.set[key] ? true : false;
};

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