public boolean isValidSudoku(char[][] board) {
		for(int i = 0; i < 9; i++){
			if(!checkCol(board, i)) return false;
			if(!checkRow(board, i)) return false;
		}
		int[] x = {1, 4, 7}, y = {1, 4, 7};
		for(int i = 0; i < 3; i++)
			for(int j = 0; j < 3; j++){
				if(!checkZone(board, x[i], y[j])) return false;
			}
		return true;
	}