POJ 1064 Cable master （二分）

题目链接: 传送门

Cable master

Time Limit: 1000MS     Memory Limit: 65536K

题目描述

有N条绳子，它们长度分别为Li。如果从它们中切割出K条长度相同的绳子的话，这K条绳子每条最长能有多长？答案保留小数点后两位。

思路

二分搜索答案

#include<iostream>
#include<cstdio>
#include<cmath>
#define EPS 1e-6
const int INF = 100000;
using namespace std;
int N,K;
double ans[10005];

bool binary(double x)
{
    int sum = 0;
    for (int i = 0;i < N;i++)
    {
        sum += (int)(ans[i] / x);
    }
    return sum >= K;
}

int main()
{
    while (scanf("%d%d",&N,&K) != EOF)
    {
        for (int i = 0;i < N;i++)
        {
            scanf("%lf",&ans[i]);
        }

        double left = 0,right = INF,mid;

        while (right - left > EPS)
        {
            mid = (left + right)/2;
            if (binary(mid))
            {
                left = mid;
            }
            else
            {
                right = mid;
            }
        }

        /*if (mid < 1)
        {
            printf("0.00\n");
        }
        else
        {
            printf("%.2lf\n",mid);
        }*/

        printf("%.2f\n",floor(right*100)/100); //防止四舍五入
    }

    return 0;
}