pku 2976 Dropping tests 01分数规划

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

题意：

给定A数组B数组，从中选择N-K个使得R最大，输出Round(100*R);

思路：

我是根据szz给的这个链接学习的，感觉讲的不错：http://lghjx.573114.com/Blog/Html/103D/275536.html

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <string>

#define CL(a,num) memset((a),(num),sizeof(a))
#define iabs(x)  ((x) > 0 ? (x) : -(x))
#define Min(a,b) (a) > (b)? (b):(a)
#define Max(a,b) (a) > (b)? (a):(b)

#define ll long long
#define inf 0x7f7f7f7f
#define MOD 1073741824
#define lc l,m,rt<<1
#define rc m + 1,r,rt<<1|1
#define pi acos(-1.0)
#define test puts("<------------------->")
#define maxn 100007
#define M 150
#define N 10007
using namespace std;
//freopen("din.txt","r",stdin);

double a[N],b[N],d[N];
const double eps = 1e-6;

int n,k;

int cmp(int a,int b)
{
    return a > b;
}
int dblcmp(double x)
{
    if (x > eps) return 1;
    else if (x < -eps) return -1;
    else return 0;
}
int main()
{
    int i;
    while (~scanf("%d%d",&n,&k))
    {
        if (!n && !k) break;
        for (i = 0; i < n; ++i) scanf("%lf",&a[i]);
        for (i = 0; i < n; ++i) scanf("%lf",&b[i]);
        double r = -1.0;
        for (i = 0; i < n; ++i)
        {
            if (a[i]/b[i] > r) r = a[i]/b[i];
        }
        int m = n - k;
        double l = 0;
        double ans = 0;
        while (dblcmp(l - r) < 0)
        {
            double mid = (l + r)/2.0;
            for (i = 0; i < n; ++i) d[i] = a[i] - mid*b[i];
            sort(d,d + n,cmp);
           // reverse(a,a + n);
            double tmp = 0;
            for (i = 0; i < m; ++i)
            tmp += d[i];
            if (tmp >= 0)
            {
                ans = mid;
                l = mid;
            }
            else r = mid;
        }
        printf("%.0lf\n",ans*100);
    }
    return 0;
}