三分板子

分手后的思念是犯贱 2021-11-01 14:40 287阅读 0赞

B - Light Bulb  
Time Limit:1000MS Memory Limit:32768KB 64bit IO Format:%lld  
& %llu  
Submit Status Practice ZOJ  
3203

Description

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. Dis 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

3  
2 1 0.5  
2 0.5 3  
4 3 4

每次分一个 rmid

再相当于4分 算lmid

code:

//
    #include<iostream>
    #include<cstdio>
    using namespace std;
    int T;
    double H,h;
    double D;
    double F(double x)
    {
        return ((h-x)/(H-x))*D+x;
    }
    int main()
    {
        cin>>T;
        while(T--)
        {
            cin>>H>>h>>D;
            double  r=h;
            double l=0;
            double rmid=(l+r)/2;
            double lmid=(rmid+l)/2;
            while(rmid-lmid>=1e-9)
            {
                if(F(lmid)>=F(rmid))
                {
                    r=rmid;
                }
                else
                l=lmid;
             rmid=(l+r)/2;
             lmid=(rmid+l)/2;
            }
            printf("%.3lf\n",F((lmid+rmid)/2));
        }
    }

Sample Output

1.000  
0.750  
4.000

转载于:https://www.cnblogs.com/OIEREDSION/p/11275631.html