twoSum.js

// =======> Question: Two Sum <=======
// Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

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

// You can return the answer in any order.

 

// Example 1:

// Input: nums = [2,7,11,15], target = 9
// Output: [0,1]
// Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].
// Example 2:

// Input: nums = [3,2,4], target = 6
// Output: [1,2]
// Example 3:

// Input: nums = [3,3], target = 6
// Output: [0,1]
 

// Constraints:

// 2 <= nums.length <= 104
// -109 <= nums[i] <= 109
// -109 <= target <= 109
// Only one valid answer exists.
 


// =======> Solution <=======
// function twoSum(nums, target) {
//     let result = [];
//     for (let i = 0; i < nums.length; i++) {
//         for (let j = i + 1; j < nums.length; j++) {
//             if (nums[i] + nums[j] === target) {
//                 result.push(i, j);
//             }
//         }
//     }
//     return result;
// }

var twoSum = function(nums, target) {
    let sanitized = new Set(nums); // to remove all duplicates
     for(let i = 0; i < nums.length; i++){
         let substractedVal = target - nums[i];
         if(sanitized.has(substractedVal) && nums.indexOf(substractedVal) !== i){
             return [i, nums.indexOf(substractedVal)]
         } else {
             continue 
         }
     }
 };
// =======> Test <=======

console.log(twoSum([2, 7, 11, 15], 9)); // [0, 1]