Dropping tests(01分数规划)

Dropping tests
Time Limit: 1000MS   Memory Limit: 65536K
Total Submissions: 8176   Accepted: 2862

Description

In a certain course, you take n tests. If you get ai out of bi questions correct on test i, your cumulative average is defined to be

Dropping tests(01分数规划).

Given your test scores and a positive integer k, determine how high you can make your cumulative average if you are allowed to drop any k of your test scores.

Suppose you take 3 tests with scores of 5/5, 0/1, and 2/6. Without dropping any tests, your cumulative average is Dropping tests(01分数规划). However, if you drop the third test, your cumulative average becomes Dropping tests(01分数规划).

Input

The input test file will contain multiple test cases, each containing exactly three lines. The first line contains two integers, 1 ≤ n ≤ 1000 and 0 ≤ k < n. The second line contains n integers indicating ai for all i. The third line contains n positive integers indicating bi for all i. It is guaranteed that 0 ≤ ai ≤ bi ≤ 1, 000, 000, 000. The end-of-file is marked by a test case with n = k = 0 and should not be processed.

Output

For each test case, write a single line with the highest cumulative average possible after dropping k of the given test scores. The average should be rounded to the nearest integer.

Sample Input

3 1
5 0 2
5 1 6
4 2
1 2 7 9
5 6 7 9
0 0

Sample Output

83
100
题解:给你n个数,让求删除k个数后

Dropping tests(01分数规划)的最大值;01分数规划;

代码:

 #include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>
using namespace std;
const int MAXN=;
struct Node{
int a,b;
};
Node dt[MAXN];
double d[MAXN];
int n,k;
bool fsgh(double R){
double sum=;
for(int i=;i<n;i++)d[i]=dt[i].a-R*dt[i].b;
sort(d,d+n);
for(int i=n-;i>=n-k;i--)sum+=d[i];
return sum>?true:false;
}
double erfen(double l,double r){
double mid;
while(r-l>1e-){
mid=(l+r)/;
if(fsgh(mid))l=mid;
else r=mid;
}
return mid;
}
int main(){
while(scanf("%d%d",&n,&k),n|k){
double mx=;
k=n-k;
for(int i=;i<n;i++)scanf("%d",&dt[i].a);
for(int i=;i<n;i++)scanf("%d",&dt[i].b),mx=max(1.0*dt[i].a/dt[i].b,mx);
printf("%.0f\n",erfen(,mx)*);
}
return ;
}
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