Cod sursa(job #631117)
Utilizator | Data | 7 noiembrie 2011 00:35:52 | |
---|---|---|---|
Problema | Dezastru | Scor | 70 |
Compilator | c | Status | done |
Runda | Arhiva de probleme | Marime | 0.48 kb |
#include <stdio.h>
short n,a[30],k,i;
double p,b[30];
int c;
void comb (int x,int m,double p1) {
int i;
if (x==k) {
p+=p1;
c++;
return;
}
for (i=m; i<=n-k+x+1; i++) comb (x+1,i+1,p1*b[i-1]);
}
int main () {
freopen ("dezastru.in","r",stdin);
freopen ("dezastru.out","w",stdout);
scanf ("%hd%hd",&n,&k);
for (i=0; i<n; i++) scanf ("%lf",b+i);
comb (0,1,1);
printf ("%.6lf\n",p/c);
return 0;
}