fig7_5.pl

% Figure 7.5  A cryptarithmetic puzzle in CLP(FD)

% Cryptarithmetic puzzle DONALD + GERALD = ROBERT in CLP(FD)

solve( [D,O,N,A,L,D], [G,E,R,A,L,D], [R,O,B,E,R,T])  :-
  Vars = [D,O,N,A,L,G,E,R,B,T],                     		% All variables in the puzzle
  domain( Vars, 0, 9),                              		% They are all decimal digits
  all_different( Vars),                            		% They are all different
  100000*D + 10000*O + 1000*N + 100*A + 10*L + D  +
  100000*G + 10000*E + 1000*R + 100*A + 10*L + D  #=
  100000*R + 10000*O + 1000*B + 100*E + 10*R + T,
  labeling( [], Vars).