ZOJ1280 (C++)

zoj1280.cpp

#include <stdio.h>
#include <algorithm>

using namespace std; 

struct vec {
  int x,y;
};

struct line {
	vec st,ed;
};

line a[1];

bool isSameline(line p,line q) {
	p.ed.x-=p.st.x;
	p.ed.y-=p.st.y;
	q.ed.x-=p.st.x;
	q.ed.y-=p.st.y;
	int cross=p.ed.x*q.ed.y-p.ed.y*q.ed.x;
	return cross==0;
}

bool isParallel(line p,line q) {
	vec m,n;
	m.x=p.ed.x-p.st.x;
	m.y=p.ed.y-p.st.y;
	n.x=q.ed.x-q.st.x;
	n.y=q.ed.y-q.st.y;
	int cross=m.x*n.y-m.y*n.x;
	return cross==0;
}

void print_cross_point(line p,line q) {
	int a[1],b[1],c[1];
	a[0]=p.st.y-p.ed.y;
	b[0]=p.ed.x-p.st.x;
	c[0]=p.st.x*p.ed.y-p.ed.x*p.st.y;
	a[1]=q.st.y-q.ed.y;
	b[1]=q.ed.x-q.st.x;
	c[1]=q.st.x*q.ed.y-q.ed.x*q.st.y;
	double delta1=a[0]*b[1]-a[1]*b[0];
	double m=(b[0]*c[1]-c[0]*b[1])/delta1,n=(a[1]*c[0]-a[0]*c[1])/delta1;
	printf("POINT %.2f %.2f\n",m,n);
	return;
}

int main() {
	int n;
	scanf("%d\n",&n);
	printf("INTERSECTING LINES OUTPUT\n");
	for (int i=0; i<n; i++) {
		scanf("%d%d%d%d",&a[0].st.x,&a[0].st.y,&a[0].ed.x,&a[0].ed.y);
		scanf("%d%d%d%d",&a[1].st.x,&a[1].st.y,&a[1].ed.x,&a[1].ed.y);
		if (isSameline(a[0],a[1])) {
			printf("LINE\n");
		}
		else if (isParallel(a[0],a[1])) {
			printf("NONE\n");
		} 
		else print_cross_point(a[0],a[1]);
	}
	printf("END OF OUTPUT\n");
	return 0;
}