ZOJ-3488-Conic Section【8th浙江省赛】

3488-Conic Section

                    Time Limit: 2 Seconds      Memory Limit: 65536 KB

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.

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

题目链接：ZOJ-3488

题目大意：给出 ax2+bxy+cy2+dx+ey+f=0 的系数，问是什么图形

题目思路：判断a,c即可。时隔一年再写这题，还是掉到了坑里面去 注意，数字范围是实数！

以下是代码：

#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <cstring>
#include <algorithm>
#include <string>
#include <set>
#include <functional>
#include <numeric>
#include <sstream>
#include <stack>
#include <map>
#include <queue>
#include<iomanip>
using namespace std;
int main()
{
    int t;
    cin >> t;
    while(t--)
    {
        double a,b,c,d,e,f;
        cin >> a >> b >> c >> d >> e >> f;
        if (a == c) cout << "circle\n";
        if (a * c > 0 && a != c) cout << "ellipse\n";
        if (a == 0 || c == 0) cout << "parabola\n";
        if (a * c < 0 && a != c) cout << "hyperbola\n";
    }
    return 0;
}