poj 1410

来源：互联网发布：淘宝店分析编辑：程序博客网时间：2024/05/02 04:48

要考虑完全在矩形里也算是相交

用到了快速排斥实验，因为要判断线段是否相交还有一种两条线段共线的情况

#include<iostream>#include<cstdio>#include<cstring>#include<cmath>#include<vector>#include<queue>#include<algorithm>using namespace std;const double EPS=1e-10;double add(double a,double b){    if(abs(a+b)<EPS*(abs(a)+abs(b)))    return 0;    return a+b;}struct P{    double x,y;    P(){}    P(double x,double y):x(x),y(y){    }    P operator +(P p){        return P(add(x,p.x),add(y,p.y));    }    P operator -(P p){        return P(add(x,-p.x),add(y,-p.y));    }    P operator *(double d){        return P(x*d,y*d);    }    double det(P p){        return add(x*p.y,-y*p.x);    }    double dot(P p){        return add(x*p.x,y*p.y);    }};P p[10],q[10];P a,b,s,e;bool kuali(int i){if(min(q[i].x,p[i].x)>max(a.x,b.x) || min(a.x,b.x)>max(p[i].x,q[i].x) )return 0;if(min(q[i].y,p[i].y)>max(a.y,b.y) || min(a.y,b.y)>max(p[i].y,q[i].y))return 0;return 1;}bool judge(){    for(int i=0;i<4;i++)    {if(kuali(i)){        if((q[i]-a).det(b-a)*(p[i]-a).det(b-a)<=EPS  && (a-q[i]).det(p[i]-q[i])*(b-q[i]).det(p[i]-q[i])<=EPS)        return 1;}    }    return 0;}int main(){    int n;   // freopen("input.txt","r",stdin);   // freopen("output1.txt","w",stdout);    while(~scanf("%d",&n))    {        for(int i=0;i<n;i++)        {            scanf("%lf%lf%lf%lf",&a.x,&a.y,&b.x,&b.y);            scanf("%lf%lf%lf%lf",&s.x,&s.y,&e.x,&e.y);            if(s.x>e.x)            swap(s,e);            q[0]=s;            p[0].x=e.x;            p[0].y=s.y;            q[1].x=s.x;            q[1].y=e.y;            p[1]=e;            q[2]=s;            p[2].x=s.x;            p[2].y=e.y;            q[3].x=e.x;            q[3].y=s.y;            p[3]=e;            if(a.x>=min(s.x,e.x) && a.x<=max(e.x,s.x) && a.y>=min(e.y,s.y) && a.y<=max(s.y,e.y) && b.x>=min(s.x,e.x) && b.x<=max(e.x,s.x) && b.y>=min(e.y,s.y) && b.y<=max(s.y,e.y))            printf("T\n");            else            {                if(judge())                printf("T\n");                else                printf("F\n");            }        }    }    return 0;}

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