【POJ】2976 - Dropping tests 二分->最大化平均值

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <queue>
#include <algorithm>
using namespace std;

int n,k;
int a[10005],b[10005];

bool ok(double mid){
double y[10005];
for (int i=0;i<n;i++){
y[i]=a[i]-mid*b[i];
}
sort(y,y+n);
double sum=0;
for (int i=0;i<(n-k);i++){
sum+=y[n-i-1];
}
return sum>=0;
}

int main(){

while ((cin >> n >> k)&&(n||k)){
for (int i=0;i<n;i++){
cin >> a[i];
}
for (int i=0;i<n;i++){
cin >> b[i];
}
double l=0,r=1000000005;
for (int i=0;i<100;i++){
double mid=(l+r)/2;
if (ok(mid)) l=mid;
else r=mid;
}
cout << (int)(l*100+0.5) << endl;  //注意精度
}

}