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
备注: 1≤ n≤ 105 0≤ k < n 1≤ s[i],c[i] ≤ 103
示例 1 输入 3 1 1 2 3 3 2 1 输出 2.33333333333
基本的01分数规划题。
退一下公式就行。
代码：
#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int maxn=1e5+10;
double s[maxn],c[maxn];
double d[maxn];
bool pan(int n,int k,double x)
{
for(int i=1;i<=n;i++)
{
d[i]=s[i]*(c[i]-x);
}
sort(d+1,d+1+n);
double sum=0;
for(int i=k+1;i<=n;i++)
{
sum+=d[i];
}
return sum>=0;
}
int main()
{
int n,k;
scanf("%d%d",&n,&k);
for(int i=1; i<=n; i++)
{
scanf("%lf",&s[i]);
}
for(int i=1; i<=n; i++)
{
scanf("%lf",&c[i]);
}
double l=0,r=1010;
while(r-l>1e-8)
{
double mid=(l+r)/2;
if(pan(n,k,mid))
{
l=mid;
}
else r=mid;
}
printf("%.11lf\n",l);
return 0;
}
/*
3 1
1 2 3
3 2 1
*/