1. Two Sum

Description:

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].

My code:

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    var firstIndex, secondIndex, arr = [];
    for(firstIndex = 0; firstIndex < nums.length - 1; firstIndex++){
        for(secondIndex = firstIndex + 1; secondIndex < nums.length; secondIndex++){
            if(target == nums[firstIndex] + nums[secondIndex]) {
                arr.push(firstIndex);
                arr.push(secondIndex);
                return arr;
            }
        }
    }
};