poj 2976 Dropping tests

http://poj.org/problem?id=2976

通过二分 不断的移动左右边界 知道满足精度

#include<iostream>

#include<cstring>

#include<algorithm>

#include<cstdio>

#define LL long long



using namespace std;



const double eps=1e-4;

const int N=1005;

double a[N];

double b[N];

double c[N];

bool cmp(double x,double y)

{

    return x>y;

}

int main()

{

    int n,k;

    while(scanf("%d %d",&n,&k)!=EOF)

    {

        if(n==0&&k==0)

        break;

        for(int i=0;i<n;++i)

        scanf("%lf",&a[i]);

        for(int i=0;i<n;++i)

        scanf("%lf",&b[i]);

        double l=0.0;

        double r=100.0;

        double mid;

        while(r-l>eps)

        {

            mid=(l+r)/2;

            for(int i=0;i<n;++i)

            c[i]=a[i]*100.0-b[i]*mid;

            sort(c,c+n,cmp);

            double sum=0;

            for(int i=0;i<n-k;++i)

            sum+=c[i];

            if(sum>0.0)

            l=mid;

            else

            r=mid;

        }

        printf("%d\n",int(l+0.5));

    }

    return 0;

}