Obtenir la valeur minimale d'une règle dans Prolog

Question

J'essaie de résoudre le problème Knight Tour. J'ai besoin d'obtenir la position qui a le minimum de mouvements. J'ai ma règle qui calcule le nombre de coups dans une position (search_path), mais je dois obtenir le minimum de cette règle (search_path_min).

moves(X, Y, Xi, Yi, Size) :- 
    (Xi is X - 1, Yi is Y - 2 
    ; Xi is X - 1, Yi is Y + 2 
    ; Xi is X + 1, Yi is Y - 2 
    ; Xi is X + 1, Yi is Y + 2 
    ; Xi is X - 2, Yi is Y - 1 
    ; Xi is X - 2, Yi is Y + 1 
    ; Xi is X + 2, Yi is Y - 1 
    ; Xi is X + 2, Yi is Y + 1), 
    Xi > 0, 
    Yi > 0, 
    Xi =< Size*Size, 
    Yi =< Size*Size. 

posibles_moves(Size, X, Y, Tour, Xi, Yi):- 
    moves(X, Y, Xi, Yi, Size), 
    \+ member((Xi,Yi),Tour). 

posibles_moves_count(Size, X, Y, Tour, Count):- 
    findall(_, posibles_moves(Size, X, Y, Tour, Xi, Yi), Moves), 
    length(Moves, Count). 

search_path(Size, X, Y, Tour, Xi, Yi, Count):- 
    posibles_moves(Size, X, Y, Tour, Xi, Yi), 
    posibles_moves_count(Size, Xi, Yi, [(Xi,Yi)|Tour],Count). 

search_path_min(Size, X, Y, Tour, Xi, Yi):- 
    search_path(Size, X, Y, Tour, Xi, Yi, Count), 
    ? 
    ? 
    ? 
    ? 

knight_tour(Size, X, Y, Tour, Path) :- 
    length(Tour, L), 
    L =:= Size * Size - 1, 
    _Tour = [(X, Y) | Tour], 
    reverse(_Tour, Path). 

knight_tour(Size, X, Y, Tour, Path) :- 
    length(Visits, L), 
    L < Size * Size - 1, 
    search_path_min(Size, X, Y, Tour, Xi, Yi), 
    _Tour = [(X, Y) | Tour], 
    knight_tour(Size, Xi, Yi, _Tour, Path). 

Ma règle search_path Je dois obtenir le résultat qui a la valeur minimale pour la variable Count. Merci.

Answer 1

je pouvais résoudre

search_path_min(Size, X, Y, Tour, Minimum):- 
    findall(min(Xi,Yi,Count),search_path(Size,X,Y,Tour,Xi,Yi,Count),[H|Rest]), 
    search_path_min(H,Rest,Minimum). 

search_path_min(Minimum, [], Minimum). 

search_path_min(min(X,Y,C),[min(X2,Y2,C2)|Rest],Minimum):- 
    C < C2 -> search_path_min(min(X,Y,C),Rest,Minimum); 
       search_path_min(min(X2,Y2,C2),Rest,Minimum).