ZOJ3488 Conic Section（圆锥曲线）

Conic Section

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Time Limit: 2 Seconds      Memory Limit: 65536 KB

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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

上个月才回去看了高中数学老师一趟，现在又想他了，圆锥曲线！！

#include<stdio.h>
int main()
{
    int t;
    double a,b,c,d,e,f;
    while(scanf("%d",&t)!=EOF)
    {
        while(t--)
        {
            scanf("%lf%lf%lf%lf%lf%lf",&a,&b,&c,&d,&e,&f);
            if(a==c)
                printf("circle\n");
            else if(a*c>0)
                printf("ellipse\n");
            else if(a*c==0)
                printf("parabola\n");
            else
                printf("hyperbola\n");
        }
    }
    return 0;
}