1.HDU2199：Can you solve this equation?(二分)

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!

#include "stdafx.h"

#include <iostream>

#include <iomanip>

using namespace std;

int a(double x)

{

return 8 * x*x*x*x + 7 * x*x*x + 2 * x*x + 3 * x + 6;

}

int main()

{

int t = 0;

cin >> t;

while (t--)

{

double n;

cin >> n;

double low = 0.0, high = 100.0;

double mid = (low + high) / 2;

if (a(0) > n || a(100) < n)   // 0-100最小值大于n和最大值小于n时无解

{

cout << "No Solution!" << endl;

continue;

}

while (fabs(a(mid) - n) > 0.00001)     //解的值带进去得出的结果相差必须小于0.00001循环结束

{

if (a(mid) > n)

high = mid;

else

low = mid;

mid = (low + high) / 2;

}

cout << setprecision(5) << mid << endl;

}

return 0;

}