How to generated N numbers in array that sum of these numbers is equal to 0

Question

I have a code like this:

function myArr(N){

    let arr = [];

    function randomNumber(min,max) {
        if (min > max) {
            let vMin = min;
            min = parseInt(max,10);
            max = parseInt(vMin,10);
        }
        return Math.floor(Math.random()*(max-min+1)+min);
    }

    for(let i = 0; i < N; i++) {
        arr.push(randomNumber(100,-100));
    }
    return arr;
}

This function generates an array with N numbers. But I want that the sum of these generated numbers will be equal to 0. How to make it? I was thinking about conditional 'if' but I don't exactly know, how to use it in this case ... Maybe some of you know, how to do this? Thanks for any tips!

Answer 1

This is my solution, basically you do a for loop and start adding elements.

Whenever you add an element, just add the same element * -1

You will end up with an array of elements with sum 0.

function arrayOfSumZero(N) {
    let sum = 0;
    let i = N % 2 === 0 ? 0 : 1;
    let output = [];

    for (i; i < N; i++) {
        if (output.length < N) {
            sum += i;
            output.push(i);
        }

        if (sum > 0) {
            sum += i * -1;
            output.push(i * -1);
        }
    }

    return output;
}