Program to find the number of subarrays in an array that have sum 0.

subarray_sum0.js

//Goal - To find the number of sub arrays in an array whose sum is 0 

const test1 = [1,2,3, -1, -5, -3, -2, 0] 


function sum0(array) {

    let subarrays = {}
    let count = 0;
    //Iterate over the array to find subarrays corresponding to the value of i
    for(let i = array.length -1 ; i >= 0; i--) {
    //For example if i = 5, createNSubArray will return all subarrays of length 5
        let s = createNSubArray(array, i + 1)
        if(s.length > 0){
        subarrays[i] = s
        count+=s.length;
        }
    }

    console.log("FINAL", subarrays)
    console.log("FINAL", count)
    return count

}


function createNSubArray(array, n){
// This functoon iterates returns subarrays of an array corresponding to value of n
/*if array = [1,2,3] and n=2 it will return [[1,2], [1,3], [2,3]], the time complexity is O(n^2) */
    let subarrays = []
    let js = 0;
    let end = n - 1 ; 
    for(let i = 0; i < array.length; i++){
        for(let j = i + n - 1; j < array.length; j++){

            let slicedArray = array.slice(i, end);
            slicedArray.push(array[j])
            //Only add those arrays that have sum 0
            if(sum(slicedArray) == 0){
            subarrays.push(slicedArray);
            }
            js = j;
        }
        end++;
        if(n == 1){
            break;
        }




    }

    return subarrays

}

//Returns sum of an array
function sum(array){
    let sum = 0;
    for(let i = 0; i < array.length; i++){
        sum += array[i];        
    }

    return sum
}

console.log(sum0(test1))