March 12, 2010

Constraint Programming – ‘Send More Money’ in Prolog

Here is an example of a constraint program written in Prolog.

  SEND
+ MORE
------
 MONEY

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smm([S,E,N,D,M,O,R,Y], Type) :-
 domain([S,E,N,D,M,O,R,Y], 0, 9),
 S#>0, M#>0,
 all_different([S,E,N,D,M,O,R,Y]),
 sum(S,E,N,D,M,O,R,Y),
 labeling(Type, [S,E,N,D,M,O,R,Y]).
 
sum(S,E,N,D,M,O,R,Y) :-
 1000*S + 100*E + 10*N + D +
 1000*M + 100*O + 10*R + E #=
 10000*M + 1000*O + 100*N + 10*E + Y.
Comments (3)

  1. Did you use SWI Prolog? I can’t seem to compile your code.

    Comment by Adam — March 12, 2010 @ 12:26 pm

  2. I used Sicstus Prolog. To compile, you just do this

    ['filename.pl'].

    and then run smm([S,E,N,D,M,O,R,Y],[]).

    Comment by admin — March 12, 2010 @ 12:28 pm

  3. Well done.

    Comment by Levi — April 12, 2010 @ 11:21 am

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