Can you solve this equation?

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<cstdio>
#include<cmath>

double cha(double x)
{
		return 8.0*pow(x,4.0)+ 7*pow(x,3.0)+ 2.0*pow(x,2.0)+ 3.0*x +6.0;

}
int main()
{
	int t;
	scanf("%d",&t);
	while(t--)
	{
		double n;
		scanf("%lf",&n);
	     int max=cha(100.0);
		if(n<6||n>max)
		{
			printf("No solution!\n");
			continue;
		}
		double mid,l=0.0,r=100.0;
		int s=100;
		while(s--)
		{
			mid=(l+r)/2;
			if(cha(mid)==n)
			{
				break;
			}
			if(cha(mid)>=n)
			{
				r=mid;
			}
			else
			{
				l=mid;
			}
		}
		printf("%.4lf\n",mid);
	}
	return 0;
}

posted @ 2019-12-12 09:00  千金一发  阅读(85)  评论(0编辑  收藏  举报