170 Two Sum III - Data structure design.js

/**
 * initialize your data structure here
 * @constructor
 */
var TwoSum = function() {
    this.hashmap = new Map();
};

/**
 * Add the number to an internal data structure.
 * @param {number} input
 * @returns {void}
 */
TwoSum.prototype.add = function(input) {
    this.hashmap[input] = this.hashmap[input] || 0;
    this.hashmap[input]++;
};

/**
 * Find if there exists any pair of numbers which sum is equal to the value.
 * @param {number} val
 * @returns {boolean}
 */
TwoSum.prototype.find = function(val) {  
    for(var key in this.hashmap) {
        var diff = val - parseInt(key);

        if(diff === parseInt(key)){
          if(this.hashmap[diff] >= 2) {
            return true;
          }
        } else if(this.hashmap[diff] >= 1) {
            return true;
        }
    }
    
    return false;
};

/**
 * Your TwoSum object will be instantiated and called as such:
 * var twoSum = new TwoSum();
 * twoSum.add(number);
 * twoSum.find(value);
 */