1 #include <iostream>
 2 #include <cstdio>
 3 #include <cmath>
 4 #include <cstring>
 5 #include <algorithm>
 6 #include <queue>
 7 using namespace std;
 8 struct node
 9 {
10     int x, y;
11 };
12 int a[35][35], n, vis[35][35];
13 int dir[4][2] = { -1,0,1,0,0,-1,0,1
 
 };
14 void bfs(int sx,int sy)
15 {
16     node s,temp,next;
17     s.x = sx;
18     s.y = sy;
19     queue<node>q;
20     q.push(s);
21     while (!q.empty())
22     {
23         temp = q.front(); q.pop();
24         for (int i = 0; i < n; i++)
25         {
26             next.x = temp.x + dir[i][0
 
];
27             next.y = temp.y + dir[i][1];
28             if (next.x >= 0 && next.x < n&&next.y >= 0 && next.y < n&&vis[next.x][next.y]==0&&a[next.x][next.y]==0)
29             {
30                 vis[next.x][next.y] = 1;
31                 q.push(next);
 
32             }
33         }
34     }
35 }
36 int main()
37 {
38     
39     while (cin >> n)
40     {
41         for (int i = 0; i < n; i++)
42             for (int j = 0; j < n; j++)
43                 cin >> a[i][j];
44         memset(vis, 0, sizeof(vis));
45         for (int i = 0; i < n; i++)
46         {
47             if (vis[i][0] == 0&& a[i][0] == 0)
48             {
49                 vis[i][0] = 1;
50                 bfs(i, 0);
51             }
52         }
53         for (int i = 0; i < n; i++)
54         {
55             if (vis[0][i] == 0&& a[0][i] == 0)
56             {
57                 vis[0][i] = 1;
58                 bfs(0, i);
59             }
60         }
61         for (int i = 0; i < n; i++)
62         {
63             if (vis[i][n-1] == 0&&a[i][n - 1] == 0)
64             {
65                 vis[i][n-1] = 1;
66                 bfs(i, n-1);
67             }
68         }
69         for (int i = 0; i < n; i++)
70         {
71             if (vis[n-1][i] == 0&& a[n - 1][i] == 0)
72             {
73                 vis[n-1][i] = 1;
74                 bfs(n-1, i);
75             }
76         }
77         for (int i = 0; i < n; i++)
78         {
79             for (int j = 0; j < n; j++)
80             {
81                 if (vis[i][j])
82                     cout << "0";
83                 else if (a[i][j])
84                     cout << a[i][j];
85                 else
86                     cout << "2" ;
87                 if (j != n - 1)
88                     cout << " ";
89             }
90             cout << endl;
91         }
92     }
93     return 0;
94 }

P1162（BFS）