Prolog Futoshiki solver

futoshiki.pl

?- use_module(library(clpfd)).

valid5(L) :- L ins 1..5, all_different(L).

futo([
    [X11, X12, X13, X14, X15],
    [X21, X22, X23, X24, X25],
    [X31, X32, X33, X34, X35],
    [X41, X42, X43, X44, X45],
    [X51, X52, X53, X54, X55]]) :-
  valid5([X11, X12, X13, X14, X15]),
  valid5([X21, X22, X23, X24, X25]),
  valid5([X31, X32, X33, X34, X35]),
  valid5([X41, X42, X43, X44, X45]),
  valid5([X51, X52, X53, X54, X55]),

  valid5([X11, X21, X31, X41, X51]),
  valid5([X12, X22, X32, X42, X52]),
  valid5([X13, X23, X33, X43, X53]),
  valid5([X14, X24, X34, X44, X54]),
  valid5([X15, X25, X35, X45, X55]),

  % Set these as per your problem
  X13 #< X14,
  X14 #< X24,
  X32 #< X33,
  X33 #< X43,
  X43 #< X44,
  X55 #< X45,
  X53 #< X52,
  X52 #< X51,
  X55 #= 2,

  labeling([], [
    X11, X12, X13, X14, X15,
    X21, X22, X23, X24, X25,
    X31, X32, X33, X34, X35,
    X41, X42, X43, X44, X45,
    X51, X52, X53, X54, X55]),
  print([
    [X11, X12, X13, X14, X15],
    [X21, X22, X23, X24, X25],
    [X31, X32, X33, X34, X35],
    [X41, X42, X43, X44, X45],
    [X51, X52, X53, X54, X55]]).

?- futo(_).
?- halt.