牛客网第五场-A gpa 01分数规划

 

Kanade selected n courses in the university. The academic credit of the i-th course is s[i] and the score of the i-th course is c[i].

At the university where she attended, the final score of her is 

Now she can delete at most k courses and she want to know what the highest final score that can get.

输入描述:

The first line has two positive integers n,k

The second line has n positive integers s[i]

The third line has n positive integers c[i]

输出描述:

Output the highest final score, your answer is correct if and only if the absolute error with the standard answer is no more than 10-5

示例1

输入

3 1
1 2 3
3 2 1

输出

2.33333333333

说明

Delete the third course and the final score is 

 

裸裸的01分数规划，不知道，妥妥儿的

代码：

#include<bits/stdc++.h>
using namespace std;
const int maxn=1e5+10;

double mid;
double va[maxn];
int n,k;
struct nod{
    int s;
    int c;
}a[maxn];

bool doit(){
    for(int i=1;i<=n;i++) va[i]=a[i].s*(a[i].c-mid);
    sort(va+1,va+1+n);
    double sum=0;

    for(int i=k+1;i<=n;i++) sum+=va[i];
    if(sum>=0) return true;
    else return false;
}

int main(){
     scanf("%d%d",&n,&k);
     for(int i=1;i<=n;i++) scanf("%d",&a[i].s);
     for(int i=1;i<=n;i++) scanf("%d",&a[i].c);

     double l=0,r=1e3;
     while(r-l>1e-7){
        mid=(l+r)/2.0;
        if(doit()) l=mid;
        else r=mid;
     }
     printf("%.7lf\n",l);
}