Subarray with 0 sum.cpp

//Problem Link : https://practice.geeksforgeeks.org/problems/subarray-with-0-sum-1587115621/1#
    bool subArrayExists(int arr[], int n)
    {
        //using map to store the prefix sum which has appeared already.
    	unordered_map<int,bool> sumMap;
    
    	int sum = 0;
    	//iterating over the array.
    	for (int i = 0 ; i < n ; i++)
    	{
    	    //storing prefix sum.
    		sum += arr[i];
    
    		//if prefix sum is 0 or if it is already present in map then it is
    		//repeated which means there is a subarray whose sub is 0,
    		//so we return true.
    		if (sum == 0 || sumMap[sum] == true){
    			return true;
    		}
            
            //storing true in map for every prefix sum obtained.
    		sumMap[sum] = true;
    	}
    	//returning false if we don't get any subarray with 0 sum.
    	return false;
    }