Valid sudoku, 是否是有效的数独

 1 public boolean isValidSudoku(char[][] board)
 2     {
 3         if(board == null || board.length != 9 || board[0].length != 9)
 4         {
 5             return false;
 6         }
 7         
 8         //判断行
 9         for(int i = 0; i < 9; i ++)
10         {
11             boolean[] m = new boolean[9];
12             for(int j = 0; j < 9; j ++)
13             {
14                 if(board[i][j] != ‘.‘)
15                 {
16                     //if(m[(int)board[i][j]])这样写是错误的，因为(int)‘1‘不等于1.
17                     if(m[(int)(board[i][j]-‘1‘)])
18                     {
19                         return false;
20                     }
21                     m[(int)(board[i][j]-‘1‘)] = true;
22                 }
23             }
24         }
25         
26         //判断列
27         for(int i = 0; i < 9; i ++)
28         {
29             boolean[] m = new boolean[9];
30             for(int j = 0; j < 9; j ++)
31             {
32                 if(board[j][i] != ‘.‘)
33                 {
34                     if(m[(int)(board[j][i]-‘1‘)])
35                     {
36                         return false;
37                     }
38                     m[(int)(board[j][i]-‘1‘)] = true;
39                 }
40             }
41         }
42         
43         //判断3*3矩阵,总共有9个
44         for(int k = 0; k < 9; k ++)
45         {
46             boolean[] m = new boolean[9];
47             for(int i = k/3*3; i < k/3*3 + 3; i ++)
48             {
49                 for(int j = k%3*3; j < k%3*3 + 3; j ++)
50                 {
51                     if(board[i][j] != ‘.‘)
52                     {
53                         if(m[(int)(board[i][j]-‘1‘)])
54                         {
55                             return false;
56                         }
57                         m[(int)(board[i][j]-‘1‘)] = true;
58                     }
59                 }
60             }
61         }
62         
63         return true;
64     }