ZOJ1648 Circuit Board（线段相交）
裸的判断线段相交
1 #include <map> 2 #include <set> 3 #include <stack> 4 #include <queue> 5 #include <cmath> 6 #include <ctime> 7 #include <vector> 8 #include <cstdio> 9 #include <cctype> 10 #include <cstring> 11 #include <cstdlib> 12 #include <iostream> 13 #include <algorithm> 14 using namespace std; 15 #define eps 1e-12 16 #define MAXN 2005 17 #define INF 1000000007 18 #define MAX(a,b) (a > b ? a : b) 19 #define MIN(a,b) (a < b ? a : b) 20 #define mem(a) memset(a,0,sizeof(a)) 21 22 struct Point{ 23 double x,y; 24 Point(double x=0, double y=0):x(x),y(y){} 25 }; 26 27 double Cross(Point A, Point B) { return A.x*B.y - A.y*B.x;}//叉积 28 29 int N; 30 struct LINE 31 { 32 Point s, e; 33 } Line[MAXN]; 34 35 int main() 36 { 37 while(~scanf("%d", &N)) 38 { 39 for(int i=0;i<N;i++) 40 { 41 scanf("%lf%lf%lf%lf", &Line[i].s.x, &Line[i].s.y, &Line[i].e.x, &Line[i].e.y); 42 } 43 int ok = 1; 44 for(int i=0;i<N && ok;i++) 45 { 46 Point Pi = Point(Line[i].e.x-Line[i].s.x, Line[i].e.y-Line[i].s.y); 47 for(int j=i+1;j<N && ok; j++) 48 { 49 double c1 = Cross(Point(Line[j].s.x-Line[i].s.x, Line[j].s.y-Line[i].s.y), Pi); 50 double c2 = Cross(Point(Line[j].e.x-Line[i].s.x, Line[j].e.y-Line[i].s.y), Pi); 51 if(c1 * c2 < 0) 52 { 53 Point Pj = Point(Line[j].e.x-Line[j].s.x, Line[j].e.y-Line[j].s.y); 54 c1 = Cross(Point(Line[i].s.x-Line[j].s.x, Line[i].s.y-Line[j].s.y), Pj); 55 c2 = Cross(Point(Line[i].e.x-Line[j].s.x, Line[i].e.y-Line[j].s.y), Pj); 56 if (c1 * c2 < 0) ok = 0; 57 } 58 } 59 } 60 printf("%s\n",ok?"ok!":"burned!"); 61 } 62 return 0; 63 }
