Two Sum

Easy

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.

Examples:

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

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

Solution

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