@[58874__15157](/user/1113269)
```
#include<bits/stdc++.h>
using namespace std;
bool judge(int x){
for(int i=2;i*i<=x;++i){
if(x%i==0)return 0;
}
return 1;
}
int n,k,ans,num[25];
void dfs(int x,int y,int sum){
if(x==n+1){
if(y==k&&judge(sum)==1)++ans;
return;
}
if(y<k)dfs(x+1,y+1,sum+num[x]);
dfs(x+1,y,sum);
return;
}
int main(){
cin>>n>>k;
for(int i=1;i<=n;++i){
cin>>num[i];
}
dfs(1,0,0);
cout<<ans;
return 0;
}
```
by YZHcsp @ 2024-04-18 17:51:08