twoSum.js

/*
Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

*/

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
 
const twoSum = function(nums, target) {
    let map = {};
    for (let i = 0; i < nums.length; i++) {
        if (map[target - nums[i]] !== undefined) {
          return [map[target-nums[i]], i];
        }
        if (map[nums[i]] === undefined) {
            map[nums[i]] = i;
        }
    }
    return false;
};