HDU 2199 Can you solve this equation?

　　　　　　　Can you solve this equation?

 

Problem Description

Now,given the equation 8*x^4 + 7*x^3 + 2*x^2 + 3*x + 6 == Y,can you find its solution between 0 and 100;
Now please try your lucky.

 

 

Input

The first line of the input contains an integer T(1<=T<=100) which means the number of test cases. Then T lines follow, each line has a real number Y (fabs(Y) <= 1e10);

 

 

Output

For each test case, you should just output one real number(accurate up to 4 decimal places),which is the solution of the equation,or “No solution!”,if there is no solution for the equation between 0 and 100.

 

 

Sample Input

2

100

-4

 

 

Sample Output

1.6152

No solution!

 

#include<cstdio>
#include<algorithm>
#include<cmath>
using namespace std;

double cal(double x)
{
    return 8*x*x*x*x+7*x*x*x+2*x*x+3*x+6;
}

int main()
{
    double x,l,r;
    int t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%lf",&x);
        if(x<cal(0)||x>cal(100))
        {
            printf("No solution!\n");
            continue;
        }
        l=0,r=100;
        while(fabs(l-r)>1e-8)
        {
            double mid=(l+r)/2;
            if(cal(mid)>x)
            r=mid;
            else
            l=mid;
        }
        printf("%.4lf\n",l);
    }
    return 0;
}