Cod sursa(job #1925709)
Utilizator | Data | 13 martie 2017 16:46:11 | |
---|---|---|---|
Problema | Dezastru | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.5 kb |
#include <fstream>
#include <iomanip>
#include <algorithm>
using namespace std;
ifstream fin("dezastru.in");
ofstream fout("dezastru.out");
const int N=30;
int n, k, p[N];
double v[N];
int main()
{
fin>>n>>k;
for(int i=0;i<n;++i)
fin>>v[i], p[i]=i;
double s=0;
do
{
double pr=1;
for(int i=0;i<k;++i)
pr*=v[p[i]];
s+=pr;
} while(next_permutation(p, p+n));
fout<<fixed<<setprecision(6)<<s/6;
return 0;
}