杭电2199-----二分法

#include<stdio.h>
#include<math.h>
double cha(double x)
{
    return 8*pow(x,4) + 7*pow(x,3) + 2*pow(x,2) + 3*x + 6;
}
int main()
{
    int t;
    double left,right,mid;
    scanf("%d",&t);
    int y;
    while(t--)
    {
        scanf("%d",&y);
        left=1.0;
        right=100.0;
        if(y<cha(left)||y>cha(100))
        {
            printf("No solution!\n");
            continue ;
        }
        while((right-left)>1e-6)
        {
            mid=(left+right)/2;
            if(cha(mid)<=y)
                left=mid;
            else right=mid;
        }
        printf("%.4lf\n",(left+right)/2);
    }
    return 0;
}