OJ-Problems-Source/HDOJ/3366_autoAC.cpp
2016-09-01 20:54:35 +08:00

47 lines
969 B
C++

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
const int maxn=1100;
struct route{
double p,q;
friend bool operator < (route a,route b){
return a.p/a.q>b.p/b.q;
}
}r[maxn];
int n,m;
double dp[maxn][20];
void input(){
scanf("%d%d",&n,&m);
for(int i=0;i<n;i++){
scanf("%lf%lf",&r[i].p,&r[i].q);
}
sort(r,r+n);
for(int i=0;i<=n;i++){
for(int j=0;j<=m;j++){
dp[i][j]=0;
}
}
}
double solve(){
double ans=0;
dp[0][m]=1;
for(int i=0;i<n;i++){
for(int j=m;j>=0;j--){
ans+=dp[i][j]*r[i].p;
if(j-1>=0) dp[i+1][j-1]+=dp[i][j]*r[i].q;
dp[i+1][j]+=dp[i][j]*(1.0-r[i].p-r[i].q);
}
}
return ans;
}
int main(){
int t;
scanf("%d",&t);
for(int i=1;i<=t;i++){
input();
printf("Case %d: %.5lf\n",i,solve());
}
return 0;
}