POJ2976Dropping tests(分数规划)

传送门

题目大意：n个二元组a[i],b[i]，去掉k个，求sigma a[i]/ sigma b[i]的最大值

代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define N 1009
#define LL long long
using namespace std;
 
LL n,k;
 
LL a[N],b[N];
 
double c[N];
 
inline int read()
{
    register LL x=,f=;register char ch=getchar();
    while(ch<''||ch>'') if(ch=='-') f=-,ch=getchar();
    while(ch>=''&&ch<='')x=x*+ch-'',ch=getchar();
    return x*f;
} 
 
int main()
{
    while()
    {
        n=read();k=read();
        if(!n&&!k) break;
        for(int i=;i<=n;i++) a[i]=read();
        for(int i=;i<=n;i++) b[i]=read();
        double l=,r=;
        while(r-l>1e-)
        {
            double mid=(l+r)/,p=;
            for(int i=;i<=n;i++) c[i]=a[i]-mid*b[i];
            sort(c+,c+n+);
            for(int i=n;i>=k+;i--) p=p+c[i];
            if(p>=) l=mid;
            else r=mid;
        }
        printf("%.0f\n",l*);
    }
    return ;
}