37. 解数独

 1 public class Solution {
 2     private boolean[][] row = null;
 3     private boolean[][] col = null;
 4     private boolean[][][] palace = null;
 5 
 6     // cur表示行
 7     private boolean helper(char[][] board, int i, int j){
 8         // i行j列
 9         for (int k = 1; k < 10; k++) {
10             if (!row[i][k] && !col[j][k] && !palace[i/3][j/3][k]) {
11                 board[i][j] = (char)(k+‘0‘);
12                 row[i][k] = true;
13                 col[j][k] = true;
14                 palace[i/3][j/3][k] = true;
15                 int ii=i,jj=j;
16                 while (board[ii][jj] != ‘.‘) {
17                     if (jj < 8) {
18                         jj = jj + 1;
19                     } else if (jj == 8) {
20                         ii = ii + 1;
21                         jj = 0;
22                     }
23                     if (ii == 9) {
24                         return true;
25                     }
26                 }
27                 if(helper(board,ii,jj))
28                     return true;
29                 board[i][j] = ‘.‘;
30                 row[i][k] = false;
31                 col[j][k] = false;
32                 palace[i/3][j/3][k] = false;
33             }
34         }
35         return false;
36     }
37 
38     public void solveSudoku(char[][] board) {
39         row = new boolean[9][9+1];
40         col = new boolean[9][9+1];
41         palace = new boolean[3][3][9+1];
42         int ii = -1,jj = -1;
43         for (int i = 0; i < 9; i++) {
44             for (int j = 0; j < 9; j++) {
45                 char elem = board[i][j];
46                 if (elem == ‘.‘) {
47                     if (ii == -1 && jj == -1){
48                         ii = i;
49                         jj = j;
50                     }
51                     continue;
52                 }
53                 row[i][elem-‘0‘] = true;
54                 col[j][elem-‘0‘] = true;
55                 palace[i/3][j/3][elem-‘0‘] = true;
56             }
57         }
58         helper(board,ii,jj);
59     }
60 
61     private void print(char[][] board) {
62         for (int i = 0; i < 9; i++) {
63             for (int j = 0; j < 9; j++) {
64                 System.out.print(board[i][j]+" ");
65             }
66             System.out.println();
67         }
68     }
69 
70     public static void main(String[] args) {
71         char[][] board = {
72                 {‘5‘,‘3‘,‘.‘,‘.‘,‘7‘,‘.‘,‘.‘,‘.‘,‘.‘},
73                 {‘6‘,‘.‘,‘.‘,‘1‘,‘9‘,‘5‘,‘.‘,‘.‘,‘.‘},
74                 {‘.‘,‘9‘,‘8‘,‘.‘,‘.‘,‘.‘,‘.‘,‘6‘,‘.‘},
75                 {‘8‘,‘.‘,‘.‘,‘.‘,‘6‘,‘.‘,‘.‘,‘.‘,‘3‘},
76                 {‘4‘,‘.‘,‘.‘,‘8‘,‘.‘,‘3‘,‘.‘,‘.‘,‘1‘},
77                 {‘7‘,‘.‘,‘.‘,‘.‘,‘2‘,‘.‘,‘.‘,‘.‘,‘6‘},
78                 {‘.‘,‘6‘,‘.‘,‘.‘,‘.‘,‘.‘,‘2‘,‘8‘,‘.‘},
79                 {‘.‘,‘.‘,‘.‘,‘4‘,‘1‘,‘9‘,‘.‘,‘.‘,‘5‘},
80                 {‘.‘,‘.‘,‘.‘,‘.‘,‘8‘,‘.‘,‘.‘,‘7‘,‘9‘}
81         };
82         new Solution().solveSudoku(board);
83     }
84 }