@[Augety1111](/user/1264812) 正确代码
```cpp
#include<bits/stdc++.h>
using namespace std;
bool isprime(int a){
for(int i=2;i*i<=a;i++)if(a%i==0)return 0;
return 1;
}
long long ans,a[25],n,k;
void dfs(int m, int sum, int s){
if(m == k){
if(isprime(sum))ans++;
return ;
}
for(int i = s; i<n;i++)dfs(m+1,sum+a[i],i+1);
return ;
}
int main(){
scanf("%d%d",&n,&k);
for(int i = 0; i < n; i++)scanf("%d",&a[i]);
dfs(0, 0, 0);
printf("%d\n",ans);
return 0;
}
//The person who copied it can AK NOI
```
by Genius_physicist @ 2024-03-17 17:22:47