题目链接:http://poj.org/problem?id=1269
#include<cstdio>
#include<cstring>
#include<cmath>
#include<iostream>
#include<algorithm>
#include<queue>
using namespace std;
const int maxn = ;
const int maxe = ;
const int INF = 0x3f3f3f;
const double eps = 1e-;
const double PI = acos(-1.0); struct Point{
double x,y;
Point(double x=, double y=) : x(x),y(y){ } //构造函数
};
typedef Point Vector; Vector operator + (Vector A , Vector B){return Vector(A.x+B.x,A.y+B.y);}
Vector operator - (Vector A , Vector B){return Vector(A.x-B.x,A.y-B.y);}
Vector operator * (Vector A , double p){return Vector(A.x*p,A.y*p);}
Vector operator / (Vector A , double p){return Vector(A.x/p,A.y/p);} bool operator < (const Point& a,const Point& b){
return a.x < b.x ||( a.x == b.x && a.y < b.y);
}
int dcmp(double x){
if(fabs(x) < eps) return ;
else return x < ? - : ;
}
bool operator == (const Point& a, const Point& b){
return dcmp(a.x - b.x) == && dcmp(a.y - b.y) == ;
} double Dot(Vector A, Vector B){ return A.x*B.x + A.y*B.y; }
double Cross(Vector A, Vector B) { return A.x*B.y - A.y * B.x; }
double Length(Vector A) { return sqrt(Dot(A,A)); } Point GetLineIntersecion(Point P, Vector v,Point Q,Vector w){
Vector u = P - Q;
double t = Cross(w,u)/Cross(v,w);
return P + v*t;
} Point read_point(){
Point A;
scanf("%lf %lf",&A.x,&A.y);
return A;
} /******************************分割线*******************************/ Point P1,P2,Q1,Q2;
int N; int main()
{
// freopen("E:\\acm\\input.txt","r",stdin);
cin>>N;
printf("INTERSECTING LINES OUTPUT\n");
while(N--){
P1 = read_point();
P2 = read_point();
Q1 = read_point();
Q2 = read_point();
if(dcmp(Cross(P2-P1,Q2-Q1))==){ //平行或重合;
if(dcmp(Cross(P1-Q1,P1-Q2)) == ) printf("LINE\n");
else printf("NONE\n");
}
else{ //相交;
Point A = GetLineIntersecion(P1,P2-P1,Q1,Q2-Q1);
printf("POINT %.2f %.2f\n",A.x,A.y);
}
}
printf("END OF OUTPUT\n");
}