[Prolog] Día 3

1 files changed, 41 insertions, 0 deletions

diff --git a/prolog/queens.pl b/prolog/queens.pl
new file mode 100644
index 0000000..505ad5b
--- /dev/null
+++ b/prolog/queens.pl
@@ -0,0 +1,41 @@
+valid_queen((Row,Col)) :-
+	Range = [1,2,3,4,5,6,7,8],
+	member(Row, Range),
+	member(Col, Range).
+
+valid_board([]).
+valid_board([H|T]) :-
+	valid_queen(Head).
+	valid_board(T).
+
+rows([],[]).
+rows([(Row,_)|QueensTail, [Row|RowsTail]) :-
+	rows(QueensTail, RowsTail).
+
+cols([],[]).
+cols([(_,Col)|QueensTail, [Col|ColsTail]) :-
+	rows(QueensTail, ColsTail).
+
+diags1([],[]).
+diags1([(Row,Col)|QueensTail], [Diagonal|DiagonalsTail]) :-
+	Diagonal is Col - Row,
+	diags1(QueensTail, DiagonalsTail).
+
+diags2([],[]).
+diags2([(Row,Col)|QueensTail], [Diagonal|DiagonalsTail]) :-
+	Diagonal is Col + Row,
+	diags2(QueensTail, DiagonalsTail).
+
+eight_queens(Board) :-
+	length(Board, 8),
+	valid_board(Board),
+
+	rows(Board, Rows),
+	cols(Board, Cols),
+	diags1(Board, Diags1),
+	diags2(Board, Diags2),
+
+	fd_all_different(Rows),
+	fd_all_different(Cols),
+	fd_all_different(Diags1),
+	fd_all_different(Diags2).