Cod sursa(job #645010)
Utilizator | Data | 7 decembrie 2011 23:21:00 | |
---|---|---|---|
Problema | Dezastru | Scor | 40 |
Compilator | c | Status | done |
Runda | Arhiva de probleme | Marime | 0.53 kb |
#include <stdio.h>
char n,k,i,u;
float p,b[30];
int c=1;
void comb (int x,int m,double p1) {
if (x==k) {
p+=p1;
return;
}
int i;
for (i=m; i<=u+x; 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);
u=n-k+1;
for (i=k+1; i<=n; i++) c*=i;
for (i=1; i<=n-k; i++) c/=i;
for (i=0; i<n; i++) scanf ("%f",b+i);
comb (0,1,1);
printf ("%.6f\n",p/c);
return 0;
}