UVALive 7004-10.1训练赛

来源：互联网发布：linux关闭自启动服务编辑：程序博客网时间：2024/05/23 12:32
题意:
就是给你一个点p,再给你几个多边形的顶点,让你去判断在多边形的边上,还是内部,还是外边
模板题
CODE
#include <iostream>#include<stdlib.h>#include<string.h>#include<math.h>#include <stdio.h>using namespace std;const double eps = 1e-8;const double PI = acos(-1.0);int sgn(double x){  if(fabs(x)<eps) return 0;  if(x<0) return -1;  else return 1;}struct Point{  double x,y;  Point(){}  Point(double _x,double _y)  {    x=_x;y=_y;  }  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);  }};struct Line{  Point s,e;  Line(){}  Line(Point _s,Point _e)  {    s=_s;e=_e;  }  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);  }};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,l1.e.y)&&  sgn((l2.s-l1.e)^(l1.s-l1.e))*sgn((l2.e-l1.e)^(l1.s-l1.e))<=0&&  sgn((l1.s-l2.e)^(l2.s-l2.e))*sgn((l1.e-l2.e)^(l2.s-l2.e))<=0;}bool OnSeg(Point P,Line L){  return  sgn((L.s-P)^(L.e-P))==0&&  sgn((P.x-L.s.x)*(P.x-L.e.x))<=0&&  sgn((P.y-L.s.y)*(P.y-L.e.y))<=0;}int inPoly(Point p,Point poly[],int n){  int cnt;  Line ray,side;  cnt=0;  ray.s=p;  ray.e.y=p.y;  ray.e.x=-100000000000.0;  for(int i=0;i<n;i++)  {    side.s = poly[i];    side.e = poly[(i+1)%n];    if(OnSeg(p,side)) return 0;    if(sgn(side.s.y-side.e.y)==0)        continue;    if(OnSeg(side.s,ray))    {      if(sgn(side.s.y-side.e.y)>0) cnt++;    }    else if(OnSeg(side.e,ray))    {      if(sgn(side.e.y-side.s.y)>0) cnt++;    }    else if(inter(ray,side))        cnt++;  }  if(cnt%2==1) return 1;  else return -1;}Point a[100010];Point t;int b[100];int main(){    int T;    int n,x,y,m,s,e;    scanf("%d",&T);    while( T-- )    {        scanf("%d %lf %lf",&n,&t.x,&t.y);        for( int i = 0; i < n; i++ )        {            scanf("%d",&m);            for( int j = 0; j < m; j++ )            {                scanf("%lf %lf",&a[j].x,&a[j].y);            }            int flag = inPoly(t,a,m);            if( flag == -1 )            {                b[i] = 2;///外面            }            else if( flag == 0 )            {                b[i] = 0;///边上            }            else            {                b[i] = 1;///里面            }        }        for( int i = 0; i < n; i++ )        {             i == n-1 ? printf("%d\n",b[i]):printf("%d ",b[i]);        }    }    return 0;}
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