zoj 1648 Circuit Board

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计算几何线段相交问题，第一次写，所以没有用模版，可以先参考一下这计算几何算法概览

不建议直接套模版，还是先理解一下
过几天将计算几何专题整理一下，再搞模版

/* ***********************************************Author        :xryzEmail         :523689985@qq.comCreated Time  :3-31 21:09:06File Name     :\Users\xryz\Desktop\CircuitBoard.cpp************************************************ */#include <stdio.h>#include <string.h>#include <iostream>#include <algorithm>#include <vector>#include <queue>#include <set>#include <map>#include <string>#include <math.h>#include <stdlib.h>#include <time.h>using namespace std;int main(){   int i,j,n;    double x1[2024],x2[2024],y1[2024],y2[2024],t1,t2,t3,t4;    bool f;    while(~scanf("%d",&n))    {        for(i=0;i<n;i++)            scanf("%lf%lf%lf%lf",&x1[i],&y1[i],&x2[i],&y2[i]);        f=1;        for(i=0;i<n-1;i++)//判断线段是否分别跨立        {            for(j=i+1;j<n;j++)            {                t1=((x1[i]-x1[j])*(y2[j]-y1[j])-(y1[i]-y1[j])*(x2[j]-x1[j]))*                    ((x2[j]-x1[j])*(y2[i]-y1[j])-(y2[j]-y1[j])*(x2[i]-x1[j]));                if(t1>0)                {                    t2=((x1[j]-x1[i])*(y2[i]-y1[i])-(y1[j]-y1[i])*(x2[i]-x1[i]))*                        ((x2[i]-x1[i])*(y2[j]-y1[i])-(y2[i]-y1[i])*(x2[j]-x1[i]));                    if(t2>0) {f=0;break;}                }            }            if(!f) break;        }        if(f) printf("ok!\n");        else printf("burned!\n");    }    return 0;}

#include <stdio.h>struct Point{    double x,y;};Point a[2048],b[2048];Point operator - (Point m,Point n){    Point c;    c.x=m.x-n.x;    c.y=m.y-n.y;    return c;}double cross(Point m,Point n){    return m.x*n.y-n.x*m.y;}int main(){    int i,j,n;    int flag;    while(scanf("%d",&n)!=EOF)    {        for(i=0;i<n;i++)            scanf("%lf%lf%lf%lf",&a[i].x,&a[i].y,&b[i].x,&b[i].y);        flag=1;        for(i=0;i<n-1;i++)        {            for(j=i+1;j<n;j++)            {                if(cross(a[i]-a[j],b[j]-a[j])*cross(b[j]-a[j],b[i]-a[j])>0)                {                    if(cross(a[j]-a[i],b[i]-a[i])*cross(b[i]-a[i],b[j]-a[i])>0)                        flag=0;                }                if(flag==0) break;            }            if(flag==0) break;        }        if(flag) printf("ok!\n");        else printf("burned!\n");    }    return 0;}

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