Equation Again 最大化最小值

C - Equation Again

Time Limit:1000MS     Memory Limit:32768KB     64bit IO Format:%I64d & %I64u

Submit Status

Description

This problem’s author is too lazy to write the problem description, so he only give you a equation like X ^(eY) == (eY) ^x, and the value of Y, your task is calculate the value of X. 
Note : here e is the Natural logarithm. 

 

Input

Each line will contain one number Y(Y >= 1). Process to end of file.

 

Output

For each case, output X on one line, accurate to five decimal places, if there are many answers, output them in increasing order, if there is no answer, just output “Happy to Women’s day!”.

 

Sample Input

1

 

Sample Output

2.71828

#include <stdio.h>
#include <math.h>

const double INF=0x3f3f3f3f;
const double s=1e-9;
const double e=exp(1);
double y,Y;

bool C(double x)
{
    if((log(x)/x)<(log(e*y)/(e*y)))
        return true;
    else
        return false;
}

int main()
{
    int i,j;
    while(scanf("%lf",&y)!=EOF)
    {
        double Y=(log(e*y)/(e*y));
        if(y==1.0)
            printf("%.5lf
",e);
        else if(Y>(log(e)/e))
        {
            printf("Happy to Women’s day!
");
        }
        else
        {
            double lb=1.0,ub=e;
            for(i=1;i<=1000;i++)
            {
                double mid=(lb+ub)/2;
                if(C(mid))
                    lb=mid;
                else
                    ub=mid;
            }
            printf("%.5lf ",ub);
            lb=e,ub=INF;
            for(i=1;i<=1000;i++)
            {
                double mid=(lb+ub)/2;
                if(C(mid))
                    ub=mid;
                else
                    lb=mid;
            }
            printf("%.5lf
",lb);

        }
    }
    return 0;
}