Cable master（二分）

Cable master

Time Limit: 1000MS Memory Limit: 10000KTotal Submissions: 43176
Accepted: 9250

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 first line of the input file contains two integer numb ers 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 meter and at most 100 kilometers in length. All lengths in the input file are written with a centimeter precision, with exactly two digits after a decimal point.

Output

Write to the output file 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 file must contain the single number "0.00" (without quotes).

Sample Input

4 118.027.434.575.39

Sample Output

2.00

题解：题目大意，
有n条绳子，每条绳子有一个长度，如果从这些绳子中切割出K条长度相同的绳子，求这K条绳子的最长长度
答案精确至小数点后两位……

#include<cstdio>#include<cmath>#include<string>#include<cstring>#include<algorithm>#include<iostream>#include<cstdlib>#include<queue>#include<stack>#include<ctime>using namespace std;int x[10005];int n,m;bool check(int y)            //  检查y是否符合题意{    int ans=0;    for(int i=0; i<n; i++)        ans+=x[i]/y;    if(ans>=m)return true;    else return false;}int main(){    scanf("%d%d",&n,&m);    double a;    int s=0;    for(int i=0; i<n; i++)    {        scanf("%lf",&a);        x[i]=(int)(a*100);    //  转化为厘米（整数) 容易处理        s=max(s,x[i]);    }    int l=1,r=s,ans=0;    while(l<=r)    {        int mid=(l+r)/2;        if(check(mid))        {            ans=mid;            l=mid+1;        }        else r=mid-1;    }    printf("%.2f\n",ans/100.0);   // 注意 坑点，隐性转换不能用lf 错了好多次……（额，刚刚又试了下，c++可以用lf和f都可以过,G++只能用f，可能是因为在G++上double和float不一样吧）}