Intersection CodeForces - 21B（最大公约数gcd）

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 numbers A2, B2, C2 separated by space. All the numbers are between -100 and 100, inclusive.

Output

Print the number of points in the intersection or -1 if there are infinite number of points.

水题，分类讨论即可。

#include<stdio.h>
#include<math.h>
#include<ctype.h>
#include<stdlib.h>
#include<algorithm>
using namespace std;
int main()
{
int a1,b1,a2,b2;
double c1,c2;
while(~scanf("%d%d%lf%d%d%lf",&a1,&b1,&c1,&a2,&b2,&c2))
{
if((a1||b1)&&(a2||b2))
{
int gcd1=__gcd(a1,b1),gcd2=__gcd(a2,b2);
a1/=gcd1,b1/=gcd1,c1=c1/(double)gcd1;
a2/=gcd2,b2/=gcd2,c2=c2/(double)gcd2;
if(a1==a2&&b1==b2&&c1==c2)
printf("-1\n");
else if(a1==a2&&b1==b2&&c1!=c2)
printf("0\n");
else
printf("1\n");
}
else if(((!a1)&&(!b1)&&(c1))||((!a2)&&(!b2)&&(c2)))
printf("0\n");
else if(((!a1)&&(!b1)&&(!c1))||((!a2)&&(!b
4000
2)&&(!c2)))
printf("-1\n");
else
printf("0\n");
}
}