n=4的一些解决方案:
..0..0....0..1....0..0....0..1....0..0....0..0....0..0....0..0....0..1....0..0
..1..0....2..0....0..1....0..2....0..1....1..0....0..1....0..1....0..0....1..0
..1..0....2..3....2..0....0..3....0..0....0..0....1..1....0..0....0..1....0..0
..0..0....1..1....0..1....3..0....0..2....2..3....1..2....1..2....1..1....0..2
..2..3....1..3....3..0....1..3....3..3....1..1....2..3....1..3....2..3....0..3