Subarray with 0 sum.cpp

/*
Subarray with 0 sum
====================

Given an array of positive and negative numbers. Find if there is a subarray (of size at-least one) with 0 sum.

Example 1:
Input:
5
4 2 -3 1 6
Output: 
Yes
Explanation: 
2, -3, 1 is the subarray 
with sum 0.

Example 2:
Input:
5
4 2 0 1 6
Output: 
Yes
Explanation: 
0 is one of the element 
in the array so there exist a 
subarray with sum 0.
Your Task:
You only need to complete the function subArrayExists() that takes array and n as parameters and returns true or false depending upon whether there is a subarray present with 0-sum or not. Printing will be taken care by the drivers code.

Expected Time Complexity: O(n).
Expected Auxiliary Space: O(n).

Constraints:
1 <= N <= 104
-105 <= a[i] <= 105
*/

bool subArrayExists(int arr[], int n)
{
  unordered_set<int> prefix_sums;
  int sum = 0;
  for (int i = 0; i < n; ++i)
  {
    sum += arr[i];
    if (!sum)
      return true;
    if (prefix_sums.find(sum) != prefix_sums.end())
      return true;
    prefix_sums.insert(sum);
  }
  return false;
}