POJ 2976 Dropping tests [二分]

1.题意：同poj3111，给出一组N个有价值a，重量b的物品，问去除K个之后，剩下的物品的平均值最大能取到多少？

2.分析：二分平均值，注意是去除K个，也就是选取N-K个

3.代码：

 # include <iostream>
 # include <cstdio>
 # include <cmath>
 # include <algorithm>
 using namespace std;
 const int MAXN=;
 const double eps=1e-;
 int N,K;
 int sgn(double x)
 {
     if(fabs(x)<eps) return ;
     if(x<) return -;
     else return ;
 }
 struct Test
 {
     double a,b;
     Test(){}
     Test(double aa,double bb)
     {
         a=aa;
         b=bb;
     }
 }T[MAXN];
 void Init()
 {
     for(int i=;i<N;i++)
         scanf("%lf",&T[i].a);
     for(int i=;i<N;i++)
         scanf("%lf",&T[i].b);
 }
 void Solve()
 {
     double temp[MAXN];
     double sum;
     double l=0.0;
     double r=2.0;
     while(sgn(r-l)!=)
     {
         double mid=l+(r-l)/2.0;
         for(int i=;i<N;i++)
             temp[i]=mid*T[i].b-T[i].a;
         sort(temp,temp+N);
         sum=;
         for(int i=;i<N-K;i++)
             sum+=-temp[i];
         //printf("%lf %lf\n",mid,sum);
         if(sgn(sum)<) r=mid;
         else l=mid;
     }
     printf("%0.f\n",100.0*l);
 }
 int main()
 {
     while(scanf("%d%d",&N,&K)!=EOF)
     {
         if(N==&&K==) break;
         Init();
         Solve();
     }
     return ;
 }