获取 javascript 中总和为 0 的所有子数组？

Question

I am trying to get all subarray which have sum 0 in javascript? I am able to do that in O(n^2) like this

function getSubArray(input){

    let result =[]
    sum= 0
    let a = [];
    for(var i =0;i<input.length;i++){
        a=[];
        sum =0 ;
        for (let j = i; j < input.length; j++) {
            a.push(input[j])
            sum+=input[j];
            if(sum ===0){
                result.push(a);
            }
        }

    }

    return result

}

when I call above function console.log(getSubArray([1, 2, -3, 0, 4, -5, 2, -1])) it is printed in all subarray but in O(n^2) .

I tried to optimism this in O(n) using map

function getSubArray1(input) {

    let sum = 0,
    map = {0:[-1]};

    for (let i = 0; i < input.length; i++) {
        sum += input[i];

        if (!map[sum]) {
            map[sum] = [i];
        }else {
            map[sum].push(i)

            let val = map[sum];
            for (let j = 0; j < val.length; j++) {
                console.log(val[j])
            }
        }
    }

}

above function not working not giving all subarray? is there any way to do this?

I take the reference from here https://www.techiedelight.com/find-sub-array-with-0-sum/

Answer 1

That site has an article titled "Find subarrays with given sum in an array" . It has C++, Java, and Python implementations.

I just ported the Java (and a bit of Python) code to JavaScript.

 const main = () => { const input = [4, 2, -3, -1, 0, 4], target = 0; console.log(subarraySum(input, target)); console.log(subarraySumMap(input, target)); }; const subarraySum = (nums, k) => { const results = []; for (let start = 0; start < nums.length; start++) { let sum = 0; for (let end = start; end <= nums.length; end++) { sum += nums[end]; if (sum === k) { results.push(nums.slice(start, end + 1)); } } } return results; } const subarraySumMap = (nums, k) => { const insert = (hashMap, key, value) => hashMap.set(key, (hashMap.get(key) || []).concat(value)); const results = [], hashMap = new Map(); let sum = 0; insert(hashMap, 0, -1); for (let index = 0; index < nums.length; index++) { sum += nums[index]; if (hashMap.has(sum - k)) { let list = hashMap.get(sum - k); list.forEach(value => { results.push(nums.slice(value + 1, index + 1)); }); } insert(hashMap, sum, index); } return results; } main();

 .as-console-wrapper { top: 0; max-height: 100%;important; }

 <:-- References: --> <.-- https://leetcode.com/problems/subarray-sum-equals-k/solution/ --> <.-- https,//www,techiedelight,com/find-subarrays-given-sum-array/ --> <,-- ∀ x ⊆ ∑ { 4, 2, -3, -1, 0, 4 } = 0 -->