Zero_Sum_Subarrays.java

// { Driver Code Starts
//Initial Template for Java

/*package whatever //do not write package name here */

import java.io.*;
import java.util.*;

class GFG {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int t = sc.nextInt();
    sc.nextLine();
    while (t-- > 0) {
      int n;
      n = sc.nextInt();

      long arr[] = new long[n];

      for (int i = 0; i < n; i++) {
        arr[i] = sc.nextLong();
      }
      Solution ob = new Solution();
      System.out.println(ob.findSubarray(arr, n));
    }

  }
}


class Solution {
  public static long findSubarray(long[] arr, int n) {
    HashMap<Long, Integer> map = new HashMap<>();
    long sum = 0, count = 0;
    for (long a : arr) {
      sum += a;
      if (sum == 0)
        count++;
      if (map.containsKey(sum))
        count += map.get(sum);
      map.put(sum, map.getOrDefault(sum, 0) + 1);
    }
    return count;
  }
}