2013-04-10 23:57:08 -07:00
|
|
|
safe[q_List, n_] :=
|
|
|
|
|
With[{l = Length@q},
|
|
|
|
|
Length@Union@q == Length@Union[q + Range@l] ==
|
|
|
|
|
Length@Union[q - Range@l] == l]
|
2015-02-20 00:35:01 -05:00
|
|
|
nQueen[q_List: {}, n_] :=
|
2013-04-10 23:57:08 -07:00
|
|
|
If[safe[q, n],
|
2015-02-20 00:35:01 -05:00
|
|
|
If[Length[q] == n, {q},
|
|
|
|
|
Cases[nQueen[Append[q, #], n] & /@ Range[n],
|
|
|
|
|
Except[{Null} | {}], {2}]], Null]
|
