Can you solve this equation?（二分）

Can you solve this equation?

Time Limit : 2000/1000ms (Java/Other) Memory Limit : 32768/32768K (Java/Other)

Total Submission(s) : 61 Accepted Submission(s) : 37

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! 

题解：二分法

代码：

 1 #include<stdio.h>
 2 double abs(double x){
 3     return x>0?x:-x;
 4 }
 5 double operate(double x){
 6     return  8*x*x*x*x+7*x*x*x+2*x*x+3*x+6.0; 
 7 }
 8 double search(double y){
 9     double l=0,r=100,mid;
10     while(r-l>1e-10){mid=(l+r)/2;
11         if(operate(mid)<y)l=mid;
12         else r=mid;
13         if(abs(operate(mid)-y)<1e-10)break;
14     }
15     return mid;
16 } 
17 int main(){
18     int T;
19     double Y;
20     scanf("%d",&T);
21     while(T--){
22         scanf("%lf",&Y);
23         if(Y<operate(0)||Y>operate(100))puts("No solution!");
24         else printf("%.4lf
",search(Y));
25     }
26     return 0;
27 }