题意: 求共线,平行或交点
#include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #include <cmath> #include <queue> using namespace std; const double EPS = 1e-6; const double INF = 1e20; bool zero(double a){return -EPS<a&&a<EPS;} struct cvector{ double x,y; cvector(double a,double b){x=a,y=b;} cvector(){} }; cvector operator+(cvector a,cvector b) { return cvector(a.x+b.x,a.y+b.y); } cvector operator-(cvector a,cvector b) { return cvector(a.x-b.x,a.y-b.y); } double operator*(cvector a,cvector b) { return a.x*b.x+a.y*b.y; } cvector operator*(double a,cvector b) { return cvector(a*b.x,a*b.y); } double operator^(cvector a,cvector b) { return a.x*b.y-b.x*a.y; } double length(double t){return t>0?t:-t;} double length(cvector a){return sqrt(a*a);} struct cpoint{ double x,y; cpoint(double a,double b){x=a,y=b;} cpoint(){} }; cvector operator-(cpoint a,cpoint b) { return cvector(b.x-a.x,b.y-a.y); } double dist(cpoint a,cpoint b) { return length(b-a); } struct cline{ cpoint a,b; } l1,l2; bool parallel(cline a,cline b) { return zero((a.a-a.b)^(b.a-b.b)); } double dist(cpoint a,cline b) { return length((a-b.a)^(b.b-b.a))/length(b.b-b.a); } cpoint intersect(cline a,cline b) { double x,y; y=((b.a.x-a.a.x)*(a.b.y-a.a.y)*(b.b.y-b.a.y)+(a.b.x-a.a.x)*(b.b.y-b.a.y)*a.a.y-(a.b.y-a.a.y)*(b.b.x-b.a.x)*b.a.y)/((a.b-a.a)^(b.b-b.a)); x=((b.a.y-a.a.y)*(a.b.x-a.a.x)*(b.b.x-b.a.x)+(a.b.y-a.a.y)*(b.b.x-b.a.x)*a.a.x-(a.b.x-a.a.x)*(b.b.y-b.a.y)*b.a.x)/((b.b-b.a)^(a.b-a.a)); return cpoint(x,y); } int main() { freopen("in.txt","r",stdin); int cas; printf("INTERSECTING LINES OUTPUT\n"); scanf("%d",&cas); while(cas--) { scanf("%lf%lf%lf%lf%lf%lf%lf%lf",&l1.a.x,&l1.a.y,&l1.b.x,&l1.b.y,&l2.a.x,&l2.a.y,&l2.b.x,&l2.b.y); if(parallel(l1,l2)) { if(zero(dist(l1.a,l2))) printf("LINE\n"); else printf("NONE\n"); } else { cpoint t = intersect(l1,l2); printf("POINT %.2lf %.2lf\n",t.x,t.y); } } printf("END OF OUTPUT\n"); return 0; }