Cod sursa(job #796157)
Utilizator | Vasilut Lucian lucian666 | Data | 10 octombrie 2012 19:25:13 |
---|---|---|---|
Problema | Dezastru | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.52 kb |
//Vasilut
#include<cstdio>
#define NN 30
using namespace std;
float bst[NN][NN],a[NN],c;
int n,i,j,k;
int main()
{
freopen("dezastru.in","r",stdin);
freopen("dezastru.out","w",stdout);
scanf("%d %d",&n,&k);
for(i=1;i<=n;i++) {
scanf("%f",&a[i]); bst[i][0]=1;
}
bst[0][0]=1;
for(i=1;i<=n;i++)
{
for(j=1;j<=k;j++)
{
bst[i][j]=bst[i-1][j]+bst[i-1][j-1]*a[i];
}
}
c=1;
for(i=k+1;i<=n;i++) c=c*i;
for(i=1;i<=n-k;i++) c=c/i;
printf("%f",bst[n][k]/c);
return 0;
}