Question 2: Write a javascript function that takes an array of numbers and a target number. The function should find two different numbers in the array that, when added together, give the target number. For example: answer([1,2,3], 4)should return [1,3]

Two-Sum-Challenge.js

// Question 2: Write a javascript function that takes an array of numbers and a target number. The function should find 
// two different numbers in the array that, when added together, give the target number. For example: answer([1,2,3], 4)
// should return [1,3]


function twoSumBest(array, target) {
    const numsMap = new Map();
    for (let i = 0; i < array.length; i++) {
        if(numsMap.has(target - array[i])) {
            return [numsMap.get(target - array[i]), i];
            // get() returns a specified element associated with the specified key from the Map object.
        } else {
            numsMap.set(array[i], i);
            //  set() adds or updates an element with a specified key and value to a Map object.
        }
    }
}


console.time("Solution-4-Even more efficient solution");
twoSumBest(arr, (arr[668] + arr[1669]));
console.timeEnd("Solution-4-Even more efficient solution");

// Solution-4-Even more efficient solution: 0.103ms
// with thanks to  https://rohan-paul.github.io/javascript/2018/04/29/2-sum/