Intersecting Lines
题目链接：https://vjudge.net/problem/POJ-1269
题目：
题意：判断给出的两条线是否相等平行还是相交，若相交求出交点坐标。。水题坑点就是提交G++WA，而提交C++A了，，
1 // 2 // Created by HJYL on 2020/1/13. 3 // 5 #include<iostream> 6 #include<cstring> 7 #include<cstdio> 8 #include<cmath> 9 #define eps 1e-6 10 using namespace std; 11 struct Point 12 { 13 double x,y; 14 }; 15 struct Line 16 { 17 double a,b,c,angle; 18 Point p1,p2; 19 Line(Point s,Point e) 20 { 21 a=s.y-e.y; 22 b=e.x-s.x; 23 c=s.x*e.y-e.x*s.y; 24 angle=atan2(e.y-s.y,e.x-s.x); 25 p1=s;p2=e; 26 } 27 Line(){} 28 }; 29 Point sub(Point a,Point b) 30 { 31 Point t; 32 t.x=a.x-b.x; 33 t.y=a.y-b.y; 34 return t; 35 } 36 double Cross(Point a,Point b) 37 { 38 return a.x*b.y-b.x*a.y; 39 } 40 41 double turn(Point p1,Point p2,Point p3) 42 { 43 return Cross(sub(p2,p1),sub(p3,p1)); 44 } 45 46 bool IsEqual(Line a,Line b) 47 { 48 if(fabs(turn(a.p1,a.p2,b.p1)*turn(a.p1,a.p2,b.p2))>eps)return 0; 49 if(fabs(turn(b.p1,b.p2,a.p1)*turn(b.p1,b.p2,a.p2))>eps)return 0; 50 return 1; 51 } 52 bool IsParallel(Line a,Line b) 53 { 54 if(fabs(Cross(sub(a.p1,a.p2),sub(b.p1,b.p2)))<eps)return 1; 55 return 0; 56 } 57 Point Intersection(Line a,Line b) 58 { 59 double k1,k2,t; 60 k1=Cross(sub(a.p2,b.p1),sub(b.p2,b.p1)); 61 k2=Cross(sub(b.p2,b.p1),sub(a.p1,b.p1)); 62 t=k1/(k1+k2); 63 Point ans; 64 ans.x=a.p2.x+(a.p1.x-a.p2.x)*t; 65 ans.y=a.p2.y+(a.p1.y-a.p2.y)*t; 66 return ans; 67 } 68 int main() 69 { 70 //freopen("text","r",stdin); 71 int T; 72 scanf("%d",&T); 73 printf("INTERSECTING LINES OUTPUT "); 74 Line s1,s2; 75 while(T--) 76 { 77 scanf("%lf%lf%lf%lf%lf%lf%lf%lf",&s1.p1.x,&s1.p1.y,&s1.p2.x,&s1.p2.y,&s2.p1.x,&s2.p1.y,&s2.p2.x,&s2.p2.y); 78 if(IsEqual(s1,s2)) 79 printf("LINE "); 80 else if(IsParallel(s1,s2)) 81 printf("NONE "); 82 else 83 { 84 Point cc=Intersection(s1,s2); 85 printf("POINT %.2lf %.2lf ",cc.x,cc.y); 86 } 87 } 88 printf("END OF OUTPUT "); 89 return 0; 90 91 }