HDU 2899 Strange fuction

Now, here is a fuction:
F(x) = 6 * x^7+8*x^6+7*x^3+5*x^2-y*x (0 <= x <=100)
Can you find the minimum value when x is between 0 and 100.

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 only one real numbers Y.(0 < Y <1e10)

Output

Just the minimum value (accurate up to 4 decimal places),when x is between 0 and 100.

Sample Input

2
100
200

Sample Output

-74.4291
-178.8534

[分析]
三分入门。
挺简单的就不赘述了，不懂三分的话，看一下上一篇文章就懂了。

[代码]

#include<cstdio>#include<cmath>const double eps = 1e-6;double y;double solve(double a){    return 6 * pow(a, 7) + 8 * pow(a, 6) + 7 * pow(a, 3) + 5 * pow(a, 2) - a*y;//F(x) = 6 * x^7+8*x^6+7*x^3+5*x^2-y*x (0 <= x <=100) }int main(){    int t;    scanf("%d", &t);    while (t--)    {        scanf("%lf", &y);        double low = 0, high = 100;        double mid, midmid;        while (low + eps < high)        {            mid = (low + high) / 2.0;            midmid = (mid + high) / 2.0;            double vmid = solve(mid);            double vmidmid = solve(midmid);            if (vmid < vmidmid)high = midmid;            else low = mid;        }        printf("%.4lf\n", solve(low));    }}