num(0).
num(1).
num(2).
num(3).
num(4).
num(5).
num(6).
num(7).
num(8).
num(9).

key([K1,K2,K3]) :- num(K1),num(K2),num(K3).

right_numbers([], [], 0).
right_numbers([S|As], [S|Ss], R) :- right_numbers(As, Ss, R2), R is R2+1.
right_numbers([A|As], [S|Ss], R) :- A \= S, right_numbers(As, Ss, R).

exact_try(Attempt, Secret, R) :- key(Attempt),
                                 key(Secret),
                                 right_numbers(Attempt, Secret, R).

lazy_try(Attempt, Secret, R) :- key(Attempt),
                                key(Secret),
                                intersection(Attempt, Secret, Intersection),
                                length(Intersection, R).

try(Attempt, Secret, R1, R2) :- exact_try(Attempt, Secret, R1),
                                lazy_try(Attempt, Secret, R2).

crack(Secret) :- try([6,8,2], Secret, 1, 1),
                try([6,1,4], Secret, 0, 1),
                try([2,0,6], Secret, 0, 2),
                try([7,3,8], Secret, 0, 0),
                try([7,8,0], Secret, 0, 1).