poj 1266 Cover an Arc.

 1 #include<iostream>
 2 #include<algorithm>
 3 #include<stdio.h>
 4 #define max(a,b) a>b?a:b
 5 #define min(a,b) a>b?b:a
 6 #include<math.h>
 7 using namespace std;
 8 #define eps 1e-8
 9 struct point{double x,y;};
10 struct line {point a,b;};
11 point a,b,c;
12 double xmult(point p1,point p2,point p0){
13  return (p1.x-p0.x)*(p2.y-p0.y)-(p2.x-p0.x)*(p1.y-p0.y);
14 }
15 bool pp(point p)
16 {
17     double t1,t2;
18     t1=(xmult(a,c,b));
19     t2=(xmult(a,p,b));
20     if ((t1<0&&t2<0)||(t1>0&&t2>0)) return true;
21     return false;
22 }
23 double distan (point p1,point p2)
24 {
25     return sqrt((p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y));
26 }
27 point inter(line u,line v)
28 {
29     point ret = u.a;
30     double t = ((u.a.x-v.a.x)*(v.a.y-v.b.y)-(u.a.y-v.a.y)*(v.a.x-v.b.x))/((u.a.x-u.b.x)*(v.a.y-v.b.y)-(u.a.y-u.b.y)*(v.a.x-v.b.x));
31     ret.x +=(u.b.x-u.a.x)*t;
32     ret.y +=(u.b.y-u.a.y)*t;
33     return ret;
34 }
35 point circle(point a,point b,point c )
36 {
37     line u,v;
38     u.a.x =(a.x+b.x)/2;
39     u.a.y = (a.y+b.y)/2;
40     u.b.x = u.a.x - a.y+b.y;
41     u.b.y = u.a.y + a.x-b.x;
42     v.a.x = (a.x+c.x)/2;
43     v.a.y = (a.y+c.y)/2;
44     v.b.x = v.a.x - a.y+c.y;
45     v.b.y = v.a.y+a.x-c.x;
46     return inter(u,v);
47 }
48 int main()
49 {
50     point d,e,p;
51     int cas =1;
52     while(~scanf("%lf %lf %lf %lf %lf %lf",&a.x,&a.y,&b.x,&b.y,&c.x,&c.y))
53     {
54         d = circle(a,b,c);
55         double bj = distan(d,a);
56         double maxx,maxy,minx,miny;
57         double dd=d.x,yy=d.y;
58         int ax,bx,cx,ay,by,cy;
59         maxx=max(a.x,b.x);
60         maxx=max(maxx,c.x);
61         minx=min(a.x,b.x);
62         minx=min(minx,c.x);
63         maxy=max(a.y,b.y);
64         maxy=max(maxy,c.y);
65         miny=min(a.y,b.y);
66         miny=min(miny,c.y);
67         p.x=d.x-bj;
68         p.y=d.y;
69         if(pp(p))
70             minx=p.x;
71         p.x=d.x+bj;
72         if(pp(p))
73             maxx=p.x;
74         p.x=d.x;
75         p.y=d.y-bj;
76         if(pp(p))
77             miny=p.y;
78         p.y=d.y+bj;
79         if(pp(p))
80             maxy=p.y;
81         cx=(long)ceil(maxx-eps)-(long)floor(minx+eps);
82         cy=(long)ceil(maxy-eps)-(long)floor(miny+eps);
83         printf("%d\n",cx*cy);
84     }
85     return 0;
86 }