题目链接：http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=4311
The conic sections are the nondegenerate curves generated by the intersections of a plane with one or two nappes of a cone. For a plane perpendicular to the axis of the cone, a circle
is produced. For a plane that is not perpendicular to the axis and that intersects only a single nappe, the curve produced is either an ellipse or a parabola. The curve produced by a plane intersecting both nappes is a hyperbola.
| conic section | equation |
|---|---|
| circle | x2+y2=a2 |
| ellipse | x2/a2+y2/b2=1 |
| parabola | y2=4ax |
| hyperbola | x2/a2-y2/b2=1 |
Input
There are multiple test cases. The first line of input is an integer T ≈ 10000 indicating the number of test cases.
Each test case consists of a line containing 6 real numbers a, b, c, d, e, f. The absolute value of any number never
exceeds 10000. It‘s guaranteed that a2+c2>0, b=0, the conic section exists and it is non-degenerate.
Output
For each test case, output the type of conic section ax2+bxy+cy2+dx+ey+f=0. See sample for more details.
Sample Input
5 1 0 1 0 0 -1 1 0 2 0 0 -1 0 0 1 1 0 0 1 0 -1 0 0 1 2 0 2 4 4 0
Sample Output
circle ellipse parabola hyperbola circle
References
- Weisstein, Eric W. "Conic Section." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/ConicSection.html
Author: WU, Zejun
Contest: The 8th Zhejiang Provincial Collegiate Programming Contest
PS:
不要想的太复杂！
代码如下：
#include<cstdio>
int main()
{
int t,n;
double a,b,c,d,e,f;
while(~scanf("%d",&t))
{
while(t--)
{
scanf("%lf%lf%lf%lf%lf%lf",&a,&b,&c,&d,&e,&f);
if( a == c)
printf("circle\n");
else if( a == 0 || c == 0 )
printf("parabola\n");
else if( a * c < 0 )//异号
printf("hyperbola\n");
//else if(a!=c && a*c > 0)
else
printf("ellipse\n");
}
}
return 0;
}