two-sum.js

// TWO SUM
// Given an array of integer nums and an integer target,
// return indices of the two numbers such that they add up to target.

// Input: nums = [2,7,11,15], target = 9
// Output: [0,1] ( Because nums[0] + nums[1] == 9,we return [0,1]
// Input: nums = [3,2,4], target = 6
// Output: [1,2]

// Brute force solution
// const twoSumOne = function (nums, target) {
//     for (let i = 0; i < nums.length; i++) {
//         for (let j = i + 1; j < nums.length; i++) {
//             // logic
//             if (nums[i] + nums[j] === target) return [i, j];
//         }
//     }
// }

// console.log(twoSum([2, 7, 11, 15], 9));

// [3,2,4] 3+2, 3+4, 2+4 => 7,7,6

// Using JS objects
const twoSum = function (nums, target) {
    let obj = {};

    for (let i = 0; i < nums.length; i++) {
        let n = nums[i]

        if (obj[target - n] >= 0) {
            return [obj[target - n], i]
        } else {
            obj[n] = i;
        }
    }
}

console.log(twoSum([2, 7, 11, 15], 26));

// {
//     "2"
//     "7"
//     "11"
//     "15"
// }