prolog - 使用 Prolog 解决脑筋急转弯 (Master Mind)

Question

一位同事与我们的 whatsapp 群组分享了这个:

This lock has a 3 digit code.
Can you guess it using only these hints?

我们使用类似于真值表的方法解决了这个问题。不过，我很好奇，这在 Prolog 中是如何解决的？

Answer 1

check 谓词的直接编码:

check( Solution, Guess, NValues, NPlaces ) :-
    Solution = [A,B,C],
    Guess   = [X,Y,Z],
    findall( t, (member(E, Guess), member(E, Solution)), Values ),
    length( Values, NValues ),
    ( A=X -> V1    is 1    ; V1      is 0  ),
    ( B=Y -> V2     is 1+V1 ; V2      is V1 ),
    ( C=Z -> NPlaces is 1+V2 ; NPlaces is V2 ).

然后简单地抄录线索，不涉及创意:

puzzle( [A,B,C] ):-
    findall( X, between(0,9,X), XS ),
    select(A,XS,RA), select(B,RA,RB), member(C,RB),
    /* "291": one digit is right and in its place
       "245": one digit is right but in the wrong place
       "463": two digits are right but both are in the wrong place
       "578": all digits are wrong
       "569": one digit is right but in the wrong place */
    check( [A,B,C], [2,9,1], 1, 1 ),
    check( [A,B,C], [2,4,5], 1, 0 ),
    check( [A,B,C], [4,6,3], 2, 0 ),
    check( [A,B,C], [5,7,8], 0, 0 ),
    check( [A,B,C], [5,6,9], 1, 0 ).

运行它:

<i>23 ?- time( puzzle(X) ).
/* 13,931 inferences, 0.000 CPU in 0.000 seconds (?% CPU, Infinite Lips) */
X = [3, 9, 4] <b>;</b>
/* 20,671 inferences, 0.000 CPU in 0.000 seconds (?% CPU, Infinite Lips) */
<b>false.</b></i>