Valid Sudoku

Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.

The Sudoku board could be partially filled, where empty cells are filled with the character '.'.

A partially filled sudoku which is valid.

Note:

A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.

连着几天没敲代码，感觉还是有点手生。数独题，不是很难，但也花了一些时间。

代码：

package code;

public class Sudoku {

	public static void main(String[] args) {
		char [][] board ={
				{'.','8','7','6','5','4','3','2','1'},
				{'2','.','.','.','.','.','.','.','.'},
				{'3','.','.','.','.','.','.','.','.'},
				{'4','.','.','.','.','.','.','.','.'},
				{'5','.','.','.','.','.','.','.','.'},
				{'6','.','.','.','.','.','.','.','.'},
				{'7','.','.','.','.','.','.','.','.'},
				{'8','.','.','.','.','.','.','.','.'},
				{'9','.','.','.','.','.','.','.','.'},}
		;

		System.out.print("res:"+ new Sudoku().isValidSudoku(board));
		
	}

	// row column 3*3
	public boolean isValidSudoku(char[][] board) {
		int sets = board.length;
		boolean[] exist_x = new boolean[10];
		boolean[] exist_y = new boolean[10];
		for (int i = 0; i < exist_x.length; i++) {
			exist_x[i] = false;
			exist_y[i] = false;
		}
		// row column
		for (int i = 0; i < 9; i++) {
			// init
			for (int k = 0; k < exist_x.length; k++) {
				exist_x[k] = false;
				exist_y[k] = false;
			}
			for (int j = 0; j < 9; j++) {
				// row
				if (board[i][j] != '.') {
					int num_x = Integer.parseInt(board[i][j] + "");
					if (exist_x[num_x] == true)
						return false;
					exist_x[num_x] = true;
				}

				// column
				if (board[j][i] != '.') {
					int num_y = Integer.parseInt(board[j][i] + "");
					if (exist_y[num_y] == true)
						return false;
					exist_y[num_y] = true;
				}

			}

		}

		// 3*3
		boolean[] exist = new boolean[10];

		for (int i = 0; i < exist_x.length; i++) {
			exist[i] = false;
		}
		for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 3; j++) {
				// clear
				for (int q = 0; q < exist_x.length; q++) {
					exist[q] = false;
				}
				for (int k = 0; k < 3; k++) {
					for (int t = 0; t < 3; t++) {
						if (board[3*i+k][3*j+t] != '.') {
							int num = Integer.parseInt(board[3*i+k][3*j+t] + "");
							if (exist[num] == true)
								return false;
							exist[num] = true;
						}
					}
				}
			}
		}
		return true;

	}

}