Cable master

Problem Description

Inhabitants of
the Wonderland have decided to hold a regional programming contest.
The Judging Committee has volunteered and has promised to organize
the most honest contest ever. It was decided to connect computers
for the contestants using a "star" topology - i.e. connect them all
to a single central hub. To organize a truly honest contest, the
Head of the Judging Committee has decreed to place all contestants
evenly around the hub on an equal distance from it.



To buy network cables, the Judging Committee has contacted a local
network solutions provider with a request to sell for them a
specified number of cables with equal lengths. The Judging
Committee wants the cables to be as long as possible to sit
contestants as far from each other as possible.



The Cable Master of the company was assigned to the task. He knows
the length of each cable in the stock up to a centimeter, and he
can cut them with a centimeter precision being told the length of
the pieces he must cut. However, this time, the length is not known
and the Cable Master is completely puzzled.



You are to help the Cable Master, by writing a program that will
determine the maximal possible length of a cable piece that can be
cut from the cables in the stock, to get the specified number of
pieces.

Input

The input
consists of several testcases. The first line of each testcase
contains two integer numbers N and K, separated by a space. N (1 ≤
N ≤ 10000) is the number of cables in the stock, and K (1 ≤ K ≤
10000) is the number of requested pieces. The first line is
followed by N lines with one number per line, that specify the
length of each cable in the stock in meters. All cables are at
least 1 centimeter and at most 100 kilometers in length. All
lengths in the input are written with a centimeter precision, with
exactly two digits after a decimal point.



The input is ended by line containing two 0's.

Output

For each
testcase write to the output the maximal length (in meters) of the
pieces that Cable Master may cut from the cables in the stock to
get the requested number of pieces. The number must be written with
a centimeter precision, with exactly two digits after a decimal
point.



If it is not possible to cut the requested number of pieces each
one being at least one centimeter long, then the output must
contain the single number "0.00" (without quotes).

Sample Input

4 11

8.02

7.43

4.57

5.39

0 0

Sample Output

2.00

题意：给你n根绳子，分成k段，最多分多大；

解题思路：这个和分蛋糕的那个是一个思路，除了题目难看之外别的没什么难度；二分的范围是0到sum/k；

感悟：很久没有一气呵成的代码，一遍过了，真爽啊！！！

代码：

#include

#include

#include

#define maxn 10010

#define eps 1e-8

using namespace std;

double len[maxn];

int n,k;

bool judge(int n,int k,double mid)

{

    int
cnt=0;

    for(int
i=0;i

       
cnt+=(int)(len[i]/mid);

    return
cnt>=k;

}

int main()

{

   
//freopen("in.txt", "r", stdin);

   
while(~scanf("%d%d",&n,&k)&&(n||k))

    {

       
double s=0;

       
for(int i=0;i

       
{

           
scanf("%lf",&len[i]);

           
s+=len[i];

       
}

       
s/=k;//理论上分的最大的绳子

       
double left,right,mid;

       
left=0;right=s;

       
while(right-left>=eps)

       
{

           
mid=(left+right)/2;

           
if(judge(n,k,mid))

               
left=mid;

           
else

               
right=mid;

       
}

       
printf("%.2f\n",mid);

    }

}