/** :  "Send more money" is a well-known puzzle. 
    Each of the letters, D,E,M,N,O,R,S and Y represents 
    a different digit. Moreover, when each
    letter is mapped to its corresponding digit the equation 
      SEND + MORE = MONEY holds. 
    A very naive solve is to instantiate each letter with an 
    unique digit and test the equation. 
    Since there are 8 letters to be solved, it simply explore 
    the 10*9*...*3 mappings of letters to digits.
*/












assign_digits([], _List).
assign_digits([D|Ds], List):-
        select(D, List, NewList),
        assign_digits(Ds, NewList).







solvSlow( [D,E,M,N,O,R,S,Y]) :-
	Lst = [S,E,N,D,M,O,R,Y],
	Digits = [0,1,2,3,4,5,6,7,8,9],
	assign_digits(Lst, Digits),
	M > 0,
	S > 0,
	1000*S + 100*E + 10*N + D +
	1000*M + 100*O + 10*R + E =:=
	10000*M + 1000*O + 100*N + 10*E + Y,
	write(Lst).



 % --------------------------
   /*     ?- solv([D,E,M,N,O,R,S,Y]).
          [9, 5, 6, 7, 1, 0, 8, 2]
          D = 7,
          E = 5,
          M = 1,
          N = 6,
          O = 0,
          R = 8,
          S = 9,
          Y = 2
   */