hdu 2199 Can you solve this equation?（二分法求多项式解）

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

int main(){

    int T;
    cin>>T;
    while(T--){
        double Y;
        cin>>Y;
        double L,R;
        L = 0.0,  R= 100.0;
        if(calc(L)>Y || Y>calc(R)){
            cout<<"No solution!"<<endl;
        }else{
            double mid;
            while((R-L)>(1e-10)){
                mid = (L+R) / 2;
                if(calc(mid)>Y){
                    R = mid;
                }else{
                    L = mid;
                }
            }
            mid = (R+L)/2;
            printf("%.4lf\n",mid);
        }
    }

    return 0;
}