POJ - 2976

原来是二分
谁对平均分贡献大选谁
界限<0.001,100次足矣

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
const int maxn=1010;
int n,k;
double mid;
struct Node{
	double a,b;
}w[maxn];
bool cmp(Node x,Node y){
	return x.a-x.b*mid>y.a-y.b*mid;
}
bool cheak(){
	sort(w,w+n,cmp);
	double s=0;
	for(int i=0;i<n-k;++i)
		s+=w[i].a-w[i].b*mid;
	return s>=0;
}
int main(){
	double l,r;
	int ans;
	while(scanf("%d%d",&n,&k)&&n+k){
		for(int i=0;i<n;++i)scanf("%lf",&w[i].a);
		for(int i=0;i<n;++i)scanf("%lf",&w[i].b);
		l=0;r=1;
		for(int i=0;i<100;++i){
			mid=(l+r)/2;
			if(cheak())l=mid;
			else r=mid;
		}
		ans=l*100+0.5;
		cout<<ans<<endl;
	}
	return 0;
}