poj 1269 水题

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 = 105;
const int maxe = 20000;
const int INF = 0x3f3f3f;
const double eps = 1e-8;
const double PI = acos(-1.0);

struct Point{
    double x,y;
    Point(double x=0, double y=0) : 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 0;
    else              return x < 0 ? -1 : 1;
}
bool operator == (const Point& a, const Point& b){
    return dcmp(a.x - b.x) == 0 && dcmp(a.y - b.y) == 0;
}

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
");
   while(N--){
      P1 = read_point();
      P2 = read_point();
      Q1 = read_point();
      Q2 = read_point();
      if(dcmp(Cross(P2-P1,Q2-Q1))==0){ //平行或重合；
         if(dcmp(Cross(P1-Q1,P1-Q2)) == 0)  printf("LINE
");
         else                               printf("NONE
");
      }
      else{  //相交；
         Point A = GetLineIntersecion(P1,P2-P1,Q1,Q2-Q1);
         printf("POINT %.2f %.2f
",A.x,A.y);
      }
   }
   printf("END OF OUTPUT
");
}