HDU 6055 17多校 Regular polygon（计算几何）

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<cmath>
 4 #include<algorithm>
 5 #include<string.h>
 6 using namespace std;
 7 
 8 bool vis[205][205];
 9 //把所有值都加100
10 
11 struct node
12 {
13     int x,y;
14 }point[505];
15 
16 bool cmp(node a,node b)
17 {
18     return a.x<b.x;
19 }
20 
21 bool judge(node c)
22 {
23     if(c.x>=0&&c.x<=200&&c.y>=0&&c.y<=200)
24         if(vis[c.x][c.y])
25             return true;
26     return  false;
27 }
28 
29 
30 int main()
31 {
32     int n,cnt;
33     while(~scanf("%d",&n))
34     {
35         memset(vis,false,sizeof(vis));
36         for(int i=0;i<n;i++)
37         {
38             scanf("%d%d",&point[i].x,&point[i].y);
39             point[i].x+=100;
40             point[i].y+=100;
41             vis[point[i].x][point[i].y]=true;
42         }
43         sort(point,point+n,cmp);
44         cnt=0;
45         node a,b,c,d;
46         int disx,disy;
47         for(int i=0;i<n;i++)
48         {
49             for(int j=i+1;j<n;j++)
50             {
51                 a=point[i];
52                 b=point[j];
53                 disx=abs(a.y-b.y);
54                 disy=abs(a.x-b.x);
55                 if(b.y<=a.y)
56                 {
57                     //右上
58                     c.x=b.x+disx;
59                     c.y=b.y+disy;
60                     d.x=a.x+disx;
61                     d.y=a.y+disy;
62                     if(judge(c)&&judge(d))
63                         cnt++;
64                     //左下
65                     c.x=b.x-disx;
66                     c.y=b.y-disy;
67                     d.x=a.x-disx;
68                     d.y=a.y-disy;
69                     if(judge(c)&&judge(d))
70                         cnt++;
71                 }
72                 else
73                 {
74                     //右下
75                     c.x=b.x+disx;
76                     c.y=b.y-disy;
77                     d.x=a.x+disx;
78                     d.y=a.y-disy;
79                     if(judge(c)&&judge(d))
80                         cnt++;
81                     //左上
82                     c.x=b.x-disx;
83                     c.y=b.y+disy;
84                     d.x=a.x-disx;
85                     d.y=a.y+disy;
86                     if(judge(c)&&judge(d))
87                         cnt++;
88                 }
89             }
90         }
91         printf("%d\n",cnt/4);
92     }
93     return 0;
94 }