杭电2199--Can you solve this equation?（二分）

Can you solve this equation?

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 12798 Accepted Submission(s): 5716

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!

Author

Redow

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 1 #include <cmath>
 2 #include <cstdio>
 3 #include <iostream>
 4 using namespace std;
 5 double f(double x)
 6 {
 7     return 8*x*x*x*x + 7*x*x*x + 2*x*x + 3*x + 6;
 8 } 
 9 int main()
10 {
11     int t; double y, mid;
12     scanf("%d", &t);
13     while(t--)
14     {
15         scanf("%lf", &y);
16         if(y<f(0) || y>f(100))
17         {
18             printf("No solution!
");
19             continue;
20         }
21         double left=0.0, right = 100.0;
22         while(right - left > 1e-8)
23         {
24              mid = (right + left) / 2.0;
25             if(abs(abs(f(mid))-y) < 1e-6)
26             break;
27             if(f(mid) < y) left = mid;
28             else right = mid;
29         }
30         printf("%.4lf
", mid);
31             
32     }
33     return 0;
34 }