HDU 4751 Divide Groups

题目链接

比赛时候，建图建错了。大体算法想到了，不过很多细节都没想好。

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <cmath>
 4 #include <queue>
 5 #include <algorithm>
 6 using namespace std;
 7 int flag[101];
 8 int p[101][101];
 9 int o[101][101];
10 int n,z;
11 void dfs(int x,int step)
12 {
13     int i;
14     if(z) return ;
15     for(i = 1; i <= n; i ++)
16     {
17         if(i == x) continue;
18         if(o[x][i]&&!flag[i])
19         {
20             flag[i] = step%2 + 1;
21             dfs(i,step+1);
22         }
23         else if(o[x][i]&&flag[i])
24         {
25             if(flag[i] != step%2 + 1)
26             {
27                 z = 1;
28                 return ;
29             }
30         }
31     }
32     return ;
33 }
34 int main()
35 {
36     int i,j;
37     while(scanf("%d",&n)!=EOF)
38     {
39         memset(flag,0,sizeof(flag));
40         memset(p,0,sizeof(p));
41         memset(o,0,sizeof(o));
42         for(i = 1; i <= n; i ++)
43         {
44             for(;;)
45             {
46                 scanf("%d",&j);
47                 if(j == 0) break;
48                 p[i][j] = 1;
49             }
50         }
51         for(i = 1;i <= n;i ++)
52         {
53             for(j = 1;j <= n;j ++)
54             {
55                 if(!p[i][j]||!p[j][i])
56                 o[i][j] = o[j][i] = 1;
57             }
58         }
59         z = 0;
60         for(i = 1; i <= n; i ++)
61         {
62             if(!flag[i])
63             {
64                 flag[i] = 2;
65                 dfs(i,0);
66             }
67         }
68         if(z)
69             printf("NO\n");
70         else
71             printf("YES\n");
72     }
73     return 0;
74 }

 

posted @ 2013-09-23 11:29  Naix_x  阅读(193)  评论(0)  编辑  收藏  举报