n=4的一些解决方案:
..2..1....1..1....0..2....1..0....2..1....2..1....1..0....2..2....1..0....2..2
..0..1....2..2....1..1....1..2....0..1....1..0....0..1....0..0....0..1....0..0
..1..0....2..2....1..1....1..2....2..1....1..2....1..0....1..1....2..1....0..0
..1..2....0..0....1..1....0..1....1..2....1..0....2..1....2..0....1..0....1..1
..2..1....0..0....1..1....1..2....1..2....1..2....2..1....1..1....1..0....2..2