POJ 1673 EXOCENTER OF A TRIANGLE

来源：互联网发布：求数组最大值和最小值编辑：程序博客网时间：2024/05/01 16:53

这道题就是求点的时候麻烦了点，思路还是很简单的

刚开始把向量反向写成了swap(x,y)，其实应该是x=-x,y=-y

#include<stdio.h>#include<math.h>#include<algorithm>using namespace std;const double eps=1e-8;struct Point {    double x,y;    Point(){}    Point(double xx,double yy){x=xx;y=yy;}    Point operator+(Point b){return Point(x+b.x,y+b.y);}    double operator^(const Point b)const{        return x*b.y-y*b.x;    }    Point operator-(Point b){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 &(Line b){        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;    }};double xmul(Point p0,Point p1,Point p2){    return (p1.x-p0.x)*(p2.y-p0.y)-(p2.x-p0.x)*(p1.y-p0.y);}double dist(Point a,Point b){    return sqrt((b.x-a.x)*(b.x-a.x)+(b.y-a.y)*(b.y-a.y));}Point getPoint(Point a,Point b,Point c){    Point q;    q=Point(-(b.y-a.y),b.x-a.x);    if(xmul(a,b,c)>eps) {        q.x=-q.x;        q.y=-q.y;    }    double d=dist(a,b);    q.x*=d/sqrt(q.x*q.x+q.y*q.y);    q.y*=d/sqrt(q.x*q.x+q.y*q.y);    q.x=a.x+q.x;    q.y=a.y+q.y;    return q;}Point p[3];int main(){#ifndef ONLINE_JUDGEfreopen("in.txt","r",stdin);#endif // ONLINE_JUDGE    int n;    scanf("%d",&n);    for(int i=0;i<n;i++){        scanf("%lf%lf%lf%lf%lf%lf",&p[0].x,&p[0].y,&p[1].x,&p[1].y,&p[2].x,&p[2].y);        Point c,d,r,q;        c=getPoint(p[0],p[1],p[2]);        d=getPoint(p[0],p[2],p[1]);        r=Point((c.x+d.x)/2,(c.y+d.y)/2);        c=getPoint(p[1],p[2],p[0]);        d=getPoint(p[1],p[0],p[2]);        q=Point((c.x+d.x)/2,(c.y+d.y)/2);        Point o;        o=Line(p[0],r)&Line(p[1],q);        printf("%.4f %.4f\n",o.x,o.y);    }    return 0;}

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