what is the mistake in my code
#include
using namespace std;
int subarraysum(int n,int a[] )
{
int cs=0,ms=0;
for(int i=0;i<=n;i++)
{
cs=cs+a[i];
if(cs<0)
{
cs=0;
}
ms=max(cs,ms);
}
return ms;
}
int main()
{
int t,n,j,a[n],i;
cin>>t;
for(i=1;i<=t;i++)
{
cin>>n;
for(j=1;j<=n;j++)
{
cin>>a[i];
}
int s=subarraysum(n,a);
cout<<s<<endl;
}
}