HDOJ 2199 Can you solve this equation?【水】

Can you solve this equation?

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 16573    Accepted Submission(s): 7357

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!

 

非常简单基础的二分。

简单地说就是分0~100，分到找到解为止。

#include<stdio.h>#include<math.h>#define eps 1e-6double add(double mid){return 8*pow(mid,4)+7*pow(mid,3)+2*pow(mid,2)+3*mid+6;}int main(){int T;double n;scanf("%d",&T);while(T--){scanf("%lf",&n);if(n<6||n>add(100))printf("No solution!\n");else{double l=0,r=100;double mid=(l+r)/2;while(r-l>eps){double temp=add(mid);if(temp>=n)r=mid;elsel=mid;mid=(l+r)/2;}double x=mid*10000;x+=0.5;int y=x;mid=(double)y/10000;printf("%.4lf\n",mid);}}return 0;}