hdu 2199 Can you solve this equation?

Can you solve this equation?

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 13292    Accepted Submission(s): 5937

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

2100-4

 

Sample Output

1.6152No solution!
源代码（二分查找）
//1000#include<stdio.h>#include<math.h>double f(double x){    return 8*pow(x,4)+7*pow(x,3)+2*pow(x,2)+3*x+6;}int main(){    int t;    double x1,x2,x3,y,y1,y2,y3;    scanf("%d",&t);    while(t--)    {        x1=0;        x2=100;        scanf("%lf",&y);        y1=f(x1)-y;        y2=f(x2)-y;        if(y1>0||y2<0)            printf("No solution!\n");        else        {            while(fabs(f(x1)-f(x2))>=0.00001)            {                x3=(x1+x2)/2;                y3=f(x3)-y;                if(y3>0)                   x2=x3;                else                   x1=x3;                y1=f(x1)-y;                y2=f(x2)-y;            }             printf("%.4lf\n",x3);           }            }    return 0;}