POJ1066

我永远不会忘记今天2017.8.13，一道计算几何从上午写完，改到下午4点半，出不来，然后换了一道水一点的这题，然后把变量名全改的更kuangbin的一样，二分对比代码查错，最后一个y1写成x2，一个if（）；的括号后面写了个分号，吐得血出

全程抄写kuangbin代码

#include<cstdio>
#include<cstring>
#include<cmath>
#include<queue>
#include<algorithm>
#define maxl 110
#define eps 1e-8

using namespace std;

int sgn(double x)
{
	if(fabs(x)<eps) return 0;
	if(x<0) 
		return -1;
	else
		return 1;
}

int n,ans;
struct point
{
	double x,y;
	point(double a=0,double b=0)
	{
		x=a;y=b;
	}
	point operator - (const point &b) const
	{
		return point(x-b.x,y-b.y);
	}
	double operator ^ (const point &b) const
	{
		return x*b.y-y*b.x;
	}
	double operator * (const point &b) const
	{
		return x*b.x+y*b.y;
	}
	void transxy(double b)
	{
		double tx=x,ty=y;
		x=tx*cos(b)-ty*sin(b);
		y=tx*sin(b)+ty*cos(b);
	}
} s;
point p[maxl];
struct line
{
	point s,e;
	double k;
	line () {}
	line(point a,point b)
	{
		s=a;e=b;
		k=atan2(e.y-s.y,e.x-s.x);
	}
	pair<int,point> operator & (const line &b) const
	{
		point res=s;
		if(sgn((s-e)^(b.s-b.e))==0)
		{
			if(sgn((s-b.e)^(b.s-b.e))==0)
				return make_pair(0,res);
			else
				return make_pair(1,res);
		}
		double t=((s-b.s)^(b.s-b.e))/((s-e)^(b.s-b.e));
		res.x+=(e.x-s.x)*t;
		res.y+=(e.y-s.y)*t;
		return make_pair(2,res);
	}
}a[maxl];

double dist(point a,point b)
{
	return sqrt((a-b)*(a-b));
}

bool inter(line l1,line l2)
{
	return
	max(l1.s.x,l1.e.x)>=min(l2.s.x,l2.e.x) &&
	max(l2.s.x,l2.e.x)>=min(l1.s.x,l1.e.x) &&
	max(l1.s.y,l1.e.y)>=min(l2.s.y,l2.e.y) &&
	max(l2.s.y,l2.e.y)>=min(l1.s.y,l2.e.y) &&
	sgn((l2.s-l1.s)^(l1.e-l1.s))*sgn((l2.e-l1.s)^(l1.e-l1.s))<=0 &&
	sgn((l1.s-l2.s)^(l2.e-l1.s))*sgn((l1.e-l2.s)^(l2.e-l2.s))<=0;
}

void prework()
{
	double x1,x2,y1,y2;
	for(int i=1;i<=n;i++)
	{
		scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);
		a[i]=line(point(x1,y1),point(x2,y2));
		p[2*i-1]=point(x1,y1);
		p[2*i]=point(x2,y2);
	}
	scanf("%lf%lf",&x1,&y1);
	s=point(x1,y1);
}

void mainwork()
{
	ans=1000000;
	for(int i=1;i<=2*n;i++)
	{
		int tmp=0;
		line l1=line(s,p[i]);
		for(int j=1;j<=n;j++)
		if(inter(l1,a[j]))
			tmp++;
		ans=min(ans,tmp);
	}
	line l1;
	l1=line(s,point(0,0));
	int tmp=0;
	for(int i=1;i<=n;i++)
	if(inter(l1,a[i]))
		tmp++;
	ans=min(ans,tmp+1);
	l1=line(s,point(0,100));
	tmp=0;
	for(int i=1;i<=n;i++)
	if(inter(l1,a[i]))
		tmp++;
	ans=min(ans,tmp+1);
	l1=line(s,point(100,0));
	tmp=0;
	for(int i=1;i<=n;i++)
	if(inter(l1,a[i]))
		tmp++;
	ans=min(ans,tmp+1);
	l1=line(s,point(100,100));
	tmp=0;
	for(int i=1;i<=n;i++)
	if(inter(l1,a[i]))
		tmp++;
	ans=min(ans,tmp+1);
	
}

void print()
{
	 printf("Number of doors = %d\n",ans);
}

int main()
{
	while(~scanf("%d",&n))
	{
		prework();
		mainwork();
		print();
	}
}