判断数独是否合法

class Solution {
/**
* @param board: the board
@return: wether the Sudoku is valid
*/
public boolean isValidSudoku(char[][] board) {
int r[][] = new int[9][9];
int l[][] = new int[9][9];
int a[][][] = new int[3][3][9];

for(int i=0;i<9;i++) {
for(int j=0;j<9;j++) {
r[i][j] = 0;
l[i][j] = 0;
if(i < 3 && j < 3) {
for(int k = 0; k<9; k++)
a[i][j][k] = 0;
}
}
}

for(int i=0;i<9;i++) {
for(int j=0;j<9;j++) {
if(board[i][j] == '.') continue;
int n = board[i][j] - '0';
if(n < 0 || n > 9) return false;
if(++r[i][n-1] > 1) return false;
if(++l[j][n-1] > 1) return false;
int x = i/3;
int y = j/3;
if(++a[x][y][n-1] > 1) return false;
}
}

return true;
}
};