POJ 3122 pie 二分

Time Limit:1000MS		Memory Limit:65536K
Total Submissions:9653		Accepted:3478		Special Judge

Description


My
birthday is coming up and traditionally I"m serving pie. Not just one pie, no, I have a number N of them, of various tastes and of various sizes. F of my friends are coming to my party and each of them gets a piece of pie. This should be one piece of one pie,
not several small pieces since that looks messy. This piece can be one whole pie though.

My friends are very annoying and if one of them gets a bigger piece than the others, they start complaining. Therefore all of them should get equally sized (but not necessarily equally shaped) pieces, even if this leads to some pie getting spoiled (which
is better than spoiling the party). Of course, I want a piece of pie for myself too, and that piece should also be of the same size.

What is the largest possible piece size all of us can get? All the pies are cylindrical in shape and they all have the same height 1, but the radii of the pies can be different.

Input
One line with a positive integer: the number of test cases. Then for each test case:One line
with two integers N and F with 1 ≤ N, F ≤ 10 000: the number of pies and the number of friends.One line with N integers ri with 1 ≤ ri ≤ 10 000: the radii of the pies.

Output
For each test case, output one line with the largest possible volume V such that me and my friends
can all get a pie piece of size V. The answer should be given as a floating point number with an absolute error of at most 10?3.

Sample Input

33 34 3 31 24510 51 4 2 3 4 5 6 5 4 2

Sample Output

25.13273.141650.2655

有n块蛋糕，分给f+1个人，但是每个人必须是整块（不能来自不同的两块蛋糕）。

思路：二分法，答案在总体积除以人数（sum/（f+1））到0之间寻找，满足条件切精确度足够则范围值。

#include <iostream>
#include <string.h>
#include <stdio.h>
#include <math.h>
#include <map>
#include<queue>
#define pi 3.14159265359
using namespace std;
int main()
{
int t;
cin>>t;
while(t--)
{
int n,f;
double v[10005],max=0,mid=-10000,min=0;
cin>>n>>f;
for(int i=0;i<n;i++)
{
cin>>v[i];
v[i]=v[i]*v[i]*pi;
max+=v[i];
}
max=max/(f+1);
while(fabs(min-max)>0.0001)
{
int sum=0,flag=1;
mid=(max+min)/2;
for(int i=0;i<n;i++)
{
sum+=(int)floor(v[i]/mid);
if(sum>=f+1)
{
min=mid;
flag=0;
break;
}
}
if(flag) max=mid;
}
printf("%.4lf\n",min);
}
}