牛客多校5 A-gpa（01分数规划）

gpa

 

链接：https://www.nowcoder.com/acm/contest/143/A
来源：牛客网

时间限制：C/C++ 1秒，其他语言2秒
空间限制：C/C++ 262144K，其他语言524288K
Special Judge, 64bit IO Format: %lld

题目描述

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

复制

3 1
1 2 3
3 2 1

输出

复制

2.33333333333

说明

Delete the third course and the final score is 

备注:

1≤ n≤ 10

⁵

0≤ k < n

1≤ s[i],c[i] ≤ 10

³

 

 

附01分数规划讲解：https://blog.csdn.net/hhaile/article/details/8883652

 

 

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<algorithm>
#define MAX 100005
#define INF 0x3f3f3f3f
#define MOD 1000000007
using namespace std;
typedef long long ll;

double s[MAX],c[MAX],cnt[MAX];

int main()
{
    int n,k,i;
    scanf("%d%d",&n,&k);
    for(i=1;i<=n;i++){
        scanf("%lf",&s[i]);
    }
    for(i=1;i<=n;i++){
        scanf("%lf",&c[i]);
    }
    double l=0,r=1000;
    while(r-l>0.000001){
        double mid=(l+r)/2;
        for(i=1;i<=n;i++){
            cnt[i]=s[i]*c[i]-mid*s[i];
        }
        sort(cnt+1,cnt+n+1);
        double fx=0;
        for(i=k+1;i<=n;i++){
            fx+=cnt[i];
        }
        if(fx>=0) l=mid;
        else r=mid;
    }
    printf("%f\n",l);
    return 0;
}