二分-D

D - Can you solve this equation?

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.

InputThe 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);OutputFor 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<iostream>
#include<cmath>
using namespace std;

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

int main()
{
    int t;
    double m,n;
    scanf("%d",&t);
    while(t--){
        scanf("%lf",&m);
        if(f(0)>m||f(100)<m){
            printf("No solution!
");
            continue;
        }
        double left = 0, right = 100, mid;
        while(fabs(f(mid)-m) > 1e-5){
            mid=(left + right)/2;
            if((f(mid) > m))     right = mid;    
             else if(f(mid)<m)     left=mid;
        }
        printf("%.4lf
",mid);
    }
    return 0;
}