hdu 2199 （二分）

链接：http://acm.hdu.edu.cn/showproblem.php?pid=2199

Can you solve this equation?

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 8595    Accepted Submission(s): 3957

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!

 

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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <iostream>
#include <algorithm>
#include <math.h>
#define eps 1e-8
using namespace std;

double fx(double x)
{
    return 8*pow(x,4)+7*pow(x,3)+2*x*x+3*x+6;
}

int main()
{
    int n,m,i,j;
    double y;
    double left=0,right=100,ans;
    scanf("%d",&n);
    while(n--)
    {
        scanf("%lf",&y);
        left=0.0,right=100.0;
        //ans=-100000;
        bool flag=true;
        while(right-left>eps)
        {
            double mid=(left+right)/2.0;
            if(fx(mid)-y< 0)
                 left=mid+eps;
            else right=mid-eps;
            //if()flag=false;
        }
        if(y>fx(100) || y<fx(0))
            printf("No solution!
");
        else
            printf("%.4lf
",left);
    }

}