Description
You are given two set of points. The first set is determined by the equation A1x + B1y + C1 = 0, and the second one is determined by the equation A2x + B2y + C2 = 0.
Write the program which finds the number of points in the intersection of two given sets.
Input
The first line of the input contains three integer numbers A1, B1, C1 separated by space. The second line contains three integer numbersA2, B2, C2
Output
Print the number of points in the intersection or -1
Sample Input
Input
1 1 0
2 2 0
Output
-1
Input
1 1 0
2 -2 0
Output
1
判斷兩條方程的交點個數，注意不是簡單的直線，有可能是整個平面或者空集
#include<cstdio>
#include<stack>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn = 1e5 + 10;
int a[3], b[3];
int main()
{
for (int i = 0; i < 3; i++) scanf("%d", &a[i]);
for (int i = 0; i < 3; i++) scanf("%d", &b[i]);
if (!a[0] && !a[1] && a[2] || !b[0] && !b[1] && b[2]) { printf("0\n"); return 0; }
if (a[0] * b[1] == a[1] * b[0])
{
if (!a[0] && !b[0]) printf("%d\n", a[1] * b[2] == a[2] * b[1] ? -1 : 0);
else printf("%d\n", a[0] * b[2] == a[2] * b[0] ? -1 : 0);
}
else printf("1\n");
return 0;
}