LongestSubarrayZeroSum.java

// Longest subarray zero sum
// Send Feedback
// Given an array consisting of positive and negative integers, find the length
// of the longest subarray whose sum is zero.
// Input Format:
// The first line of input contains an integer, that denotes the value of the
// size of the array. Let us denote it with the symbol N.
// The following line contains N space separated integers, that denote the value
// of the elements of the array.
// Output Format
// The first and only line of output contains length of the longest subarray
// whose sum is zero.
// Constraints:
// 0 <= N <= 10^8
// Time Limit: 1 sec
// Sample Input 1:
// 10
// 95 -97 -387 -435 -5 -70 897 127 23 284
// Sample Output 1:
// 5
// Explanation:
// The five elements that form the longest subarray that sum up to zero are:
// -387, -435, -5, -70, 897
// Note
// You don't have to print anything. Just complete the definition of the
// function given and return the value accordingly.

import java.util.HashMap;

public class Solution {

    public static int lengthOfLongestSubsetWithZeroSum(int arr[]) {
        // Write your code here
        HashMap<Integer, Integer> map = new HashMap<>();
        int maxi = 0;
        int sum = 0;
        for (int i = 0; i < arr.length; i++) {
            sum += arr[i];

            if (sum == 0) {
                maxi = i + 1;
            } else {
                if (map.containsKey(sum)) {
                    maxi = Math.max(maxi, i - map.get(sum));
                } else {
                    map.put(sum, i);
                }
            }
        }

        return maxi;
    }
}