I am getting 80/100

#1

#include <bits/stdc++.h>
using namespace std;

bool subArrayExists(int arr[], int n)
{
unordered_set sumSet;

// Traverse through array and store prefix sums 
int sum = 0; 
for (int i = 0 ; i < n ; i++) 
{ 
	sum += arr[i]; 

	// If prefix sum is 0 or it is already present 
	if (sum == 0 || sumSet.find(sum) != sumSet.end()) 
		return true; 

	sumSet.insert(sum); 
} 
return false;

}

// Driver code
int main()
{

int t;
cin>> t;
while(t--)
{
	int n;
	cin>> n;
	int arr[n];
	for(int i=0;i<n;i++)
	{
		cin>> arr[i];
	}
        if (subArrayExists(arr, n)) 
	cout << "Yes"<<endl; 
else
	cout << "No"<<endl; 
}
return 0;

}

#2
#3

hello @sunneykumar309
the logic that u applied is for subarray only.
in question they are asking u to tell whether there exisit any subset or not with 0 sum.
note subset and subarray are different things.

#4

#include <bits/stdc++.h>
using namespace std;
// Returns true if there is a subset
// of set[] with sum equal to given sum
bool isSubsetSum(int set[], int n, int sum)
{
// Base Cases
if (sum == 0)
return true;
if (n == 0)
return false;

// If last element is greater than sum,
// then ignore it
if (set[n - 1] > sum)
	return isSubsetSum(set, n - 1, sum);

/* else, check if sum can be obtained by any

of the following:
(a) including the last element
(b) excluding the last element */
return isSubsetSum(set, n - 1, sum)
|| isSubsetSum(set, n - 1, sum - set[n - 1]);
}

// Driver code
int main()
{
int t;
cin>> t;
while(t–)
{
int n;
cin>> n;
int set[n];
for(int i=0;i<n;i++)
{
cin>> set[i];
}
int sum = 0;
if (isSubsetSum(set, n, sum) == true)
printf(“Yes”);
else
printf(“No”);

}
return 0 ;

}

#5

still i am getting error
and after watching hint section i am get confused
because she is saying when the (1,2,3) then answer is 2.
How is it possible?

#6
#7

@sunneykumar309
ur approach will also consider empty subset as well .
and becuase empty subset will have 0 sum , ur code will always print yes .
but in question they are asking for non empty subset.
to resolve this issue.
maintain count of 0 sum SUBSET.
if count > 1 then print yes (1 is for empty set)
otherwise print nO

#8

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