n=4的一些解决方案:
..2..2..3..3..2..2....2..2..3..2..2..0....2..3..2..3..2..2....0..2..3..2..3..2
..2..0..3..2..0..2....2..0..2..0..2..2....3..2..0..2..0..2....2..3..3..0..2..3
..3..3..3..0..2..3....3..3..3..2..0..2....2..0..2..3..3..3....2..0..3..2..0..2
..2..3..3..2..3..2....2..2..0..2..2..2....2..2..2..0..2..2....2..2..3..3..2..2