zoj Light Bulb

最新推荐文章于 2019-02-06 14:46:21 发布

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最新推荐文章于 2019-02-06 14:46:21 发布

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原文链接：http://www.cnblogs.com/llei1573/p/3254934.html

本文介绍了一个关于计算人物影子长度最大值的问题。通过输入灯泡的高度、人物高度及灯泡到墙的距离，利用数学方法求解人物影子的最大长度，并给出了具体的实现代码。

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Light Bulb

Time Limit: 1 Second Memory Limit: 32768 KB

Compared to wildleopard's wealthiness, his brother mildleopard is rather poor. His house is narrow and he has only one light bulb in his house. Every night, he is wandering in his incommodious house, thinking of how to earn more money. One day, he found that the length of his shadow was changing from time to time while walking between the light bulb and the wall of his house. A sudden thought ran through his mind and he wanted to know the maximum length of his shadow.

Input

The first line of the input contains an integer T (T <= 100), indicating the number of cases.

Each test case contains three real numbers H, h and D in one line. H is the height of the light bulb while h is the height of mildleopard. D is distance between the light bulb and the wall. All numbers are in range from 10^-2 to 10³, both inclusive, and H - h >= 10^-2.

Output

For each test case, output the maximum length of mildleopard's shadow in one line, accurate up to three decimal places..

Sample Input

Sample Output

1.000
0.750
4.000

很好的一个3分题

#include<stdio.h>
#include<math.h>
double H,h,d;
double cal(double x)
{
     return d*(h-x)/(H-x)+x;
}
int main()
{
     int t;
    double  x;
     scanf("%d",&t);
     while(t--)
     {
          scanf("%lf %lf %lf",&H,&h,&d);
          double r=h,l=0.0,mid,midmid;
          while(r-l>1e-6)
          {
               mid=(r+l)/2;
               midmid=(mid+r)/2;
               if(cal(mid)>cal(midmid))
                    r=midmid;
               else
                    l=mid;
          }
          printf("%.3lf\n",cal(l));
     }

     return 0;
}