POJ 2540 Hotter Colder

来源：互联网发布：禁忌的边界线知乎编辑：程序博客网时间：2024/05/01 13:51
求中垂线的半平面交
注意这里出现一个'Same'之后就一直输出0.00了
#include<stdio.h>#include<math.h>using namespace std;const double eps=1e-8;struct Point {    double x,y;    Point () {};    Point (double xx,double yy) {x=xx;y=yy;};    double operator^(const Point b)const{        return x*b.y-y*b.x;    }    Point operator-(const Point b)const{        return Point(x-b.x,y-b.y);    }};struct Line {    Point s,e;    Line(){};    Line(Point ss,Point ee){s=ss;e=ee;}    Point operator &(const Line b)const {        Point res=s;        double t=((s-b.e)^(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 res;    }};int n,cnt;Point s,e,p[105],q[105];Line t;char str[100];Line getline(Point s,Point e){    Point mid,t;    mid.x=(s.x+e.x)/2;  mid.y=(s.y+e.y)/2;    t.x=e.y-mid.y;    t.y=mid.x-e.x;    t.x+=mid.x;    t.y+=mid.y;    return Line(mid,t);}void cut(Line t){    int curCnt=0;    for(int i=1;i<=cnt;i++) {        double s=(t.e-t.s)^(p[i]-t.s);        if (str[0]=='H') s=-s;        if (s<=eps) q[++curCnt]=p[i];        else {            s=(t.e-t.s)^(p[i-1]-t.s);            if (str[0]=='H') s=-s;            if (s<-eps) q[++curCnt]=t&Line(p[i],p[i-1]);            s=(t.e-t.s)^(p[i+1]-t.s);            if (str[0]=='H') s=-s;            if (s<-eps) q[++curCnt]=t&Line(p[i],p[i+1]);        }    }    cnt=curCnt;    q[0]=q[cnt];    q[cnt+1]=q[1];    for(int i=0;i<=cnt+1;i++) p[i]=q[i];    //printf("%d\n",cnt);    double area=0;    for(int i=1;i<=cnt;i++) {        area+=p[i]^p[i+1];        //printf("%f   %f\n",p[i].x,p[i].y);    }    area=fabs(area/2);    if(area>eps) printf("%.2f\n",area);    else printf("0.00\n");}int main() {#ifndef ONLINE_JUDGEfreopen("in.txt","r",stdin);#endif // ONLINE_JUDGE    s.x=0;  s.y=0;    p[1].x=0;   p[1].y=0;    p[2].x=10;   p[2].y=0;    p[3].x=10;   p[3].y=10;    p[4].x=0;   p[4].y=10;    p[5]=p[1];  p[0]=p[4];    cnt=4;    while(scanf("%lf%lf%s",&e.x,&e.y,str)!=EOF){        Line t;        t=getline(s,e);        if (str[0]=='S') cnt=0;        cut(t);        //printf("%f %f %f %f\n",t.s.x,t.s.y,t.e.x,t.e.y);        s=e;    }}
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