判断数组内是否有几个元素之和等于m

#include<iostream>
using namespace std;
int a[10001];
int f(int n,int m)
{
    if(m==0||m-a[n]==0)return 1;
    if(n==1&&m-a[n]!=0)return 0;
    else return f(n-1,m)+f(n-1,m-a[n]);
}
int main()
{
    int n,m;
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
    }
    cin>>m;
    if(f(n,m)==1)
    cout<<"yes";
    else cout<<"no";
    return 0;
}