Cod sursa(job #38021)
Utilizator | Bogdan-Cristian Tataroiu bogdan2412 | Data | 25 martie 2007 14:27:04 |
---|---|---|---|
Problema | Dezastru | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.47 kb |
#include <stdio.h>
#define MAXN 32
int N, K;
double p[MAXN];
double SUM; int NR;
void back( int k, int l, double P )
{
if (k == K)
{
NR++;
SUM += P;
return;
}
for (int i = l + 1; i <= N - K + k; i++)
back( k + 1, i, P * p[i] );
}
int main()
{
freopen("dezastru.in", "rt", stdin);
freopen("dezastru.out", "wt", stdout);
scanf("%d %d", &N, &K);
for (int i = 0; i < N; i++)
scanf("%lf", p + i);
back(0, -1, 1);
printf("%.6lf\n", SUM / NR);
return 0;
}