hdu4720Naive and Silly Muggles

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一直理解的最小覆盖圆就是外接圆。。原来还要分钝角和锐角。。。

钝角的话就为最长边的中点，对于这题分别枚举一下外接圆以及中点的圆，判一下是不是在园外。

 #include <iostream>
 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 #include<stdlib.h>
 #include<vector>
 #include<cmath>
 #include<queue>
 #include<set>
 using namespace std;
 #define N 100000
 #define LL long long
 #define INF 0xfffffff
 const double eps = 1e-;
 const double pi = acos(-1.0);
 const double inf = ~0u>>;
 struct Point
 {
     double x,y;
     Point (double x=,double y =):x(x),y(y){}
 }p[];
 struct Circle
 {
     Point center;
     double r;
 };
 typedef Point pointt;
 pointt operator - (Point a,Point b)
 {
     return Point(a.x-b.x,a.y-b.y);
 }
 int dcmp(double x)
 {
     if(fabs(x)<eps) return ;
     return x<?-:;
 }
 double dis(Point a)
 {
     return a.x*a.x+a.y*a.y;
 }
 double cross(Point a,Point b)
 {
     return a.x*b.y-a.y*b.x;
 }
 double area()
 {
     return fabs(cross(p[]-p[],p[]-p[]))/;
 }
 struct Circle Circumcircle()
 {
     Circle tmp;
     double a,b,c,c1,c2;
     double xa,ya,xb,yb,xc,yc;
     a = sqrt(dis(p[]-p[]));
     b = sqrt(dis(p[]-p[]));
     c = sqrt(dis(p[]-p[]));
     //¸ù¾Ýs = a*b*c/R/4£¬Çó°ë¾¶
     tmp.r = (a*b*c)/(area()*4.0);
     xa = p[].x;
     ya = p[].y;
     xb = p[].x;
     yb = p[].y;
     xc = p[].x;
     yc = p[].y;
     c1 = (dis(p[])-dis(p[]))/;
     c2 = (dis(p[])-dis(p[]))/;
     tmp.center.x = (c1*(ya-yc)-c2*(ya-yb))/((xa-xb)*(ya-yc)-(xa-xc)*(ya-yb));
     tmp.center.y = (c1*(xa-xc)-c2*(xa-xb))/((ya-yb)*(xa-xc)-(ya-yc)*(xa-xb));
     return tmp;
 }
 int main()
 {
     int t,i;
     cin>>t;
     int kk = ;
     while(t--)
     {
         for(i =  ;i <=  ; i++)
         scanf("%lf%lf",&p[i].x,&p[i].y);
         Circle cc = Circumcircle();
         Point pp;
         scanf("%lf%lf",&pp.x,&pp.y);
         double r = cc.r;
         r*=r;
         printf("Case #%d: ",++kk);
         if(dis(pp-cc.center)>r)
         {
             puts("Safe");
             continue;
         }
         r = dis(p[]-p[])/;
         cc.center.x = (p[].x+p[].x)/;
         cc.center.y = (p[].y+p[].y)/;
         if(dcmp(dis(p[]-cc.center)-r)<=&&dcmp(dis(pp-cc.center)-r)>)
         {
             puts("Safe");
             continue;
         }
         r = dis(p[]-p[])/;
         cc.center.x = (p[].x+p[].x)/;
         cc.center.y = (p[].y+p[].y)/;
         if(dcmp(dis(p[]-cc.center)-r)<=&&dcmp(dis(pp-cc.center)-r)>)
         {
             puts("Safe");
             continue;
         }
         r = dis(p[]-p[])/;
         cc.center.x = (p[].x+p[].x)/;
         cc.center.y = (p[].y+p[].y)/;
         if(dcmp(dis(p[]-cc.center)-r)<=&&dcmp(dis(pp-cc.center)-r)>)
         {
             puts("Safe");
             continue;
         }
         puts("Danger");
     }
     return ;
 }