我在Prolog应用程序中制作了一个游戏，射手将移动到一个相邻的方块，这个方块在一个4 x 4系统的网格上是安全的。用户可以输入他们想要去的坐标，例如，如果我输入safe_square(4,1,3,1)。弓箭手将从 4,1移动到3,1 。我想要做的是显示射手已经访问过的任何方块，方法是将它们添加到列表中，然后显示该列表。
我的代码如下：创建电路板，打印电路板，填充电路板，以及在电路板上移动。
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% square(row,col,val)
:- dynamic square/3.
:- dynamic show/1.
createBoard(N) :-
retractall(show(_)),
assert(show([[1,1]])),
retractall(square(_,_,_)),
createBoard(N,N).
testBoard :-
retractall(square(_,_,_)),
retractall(show(_)),
assert(show([[4,1]])),
assert(show([[3,1]])),
assert(show([[2,1]])),
asserta(square(1,1,[e])),
asserta(square(1,2,[e])),
asserta(square(1,3,[s])),
asserta(square(1,4,[e])),
asserta(square(2,1,[e])),
asserta(square(2,2,[b,s])),
asserta(square(2,3,[w])),
asserta(square(2,4,[g,s])),
asserta(square(3,1,[b])),
asserta(square(3,2,[p])),
asserta(square(3,3,[g,b,s])),
asserta(square(3,4,[x])),
asserta(square(4,1,[a,e])),
asserta(square(4,2,[b])),
asserta(square(4,3,[e])),
asserta(square(4,4,[g])).
createBoard(0,_).
createBoard(Row,Col) :-
createCol(Row,Col),
NextRow is Row -1,
createBoard(NextRow,Col).
createCol(Row,1) :-
assertz(square(Row,1,[e])).
createCol(CurrentRow,CurrentCol) :-
assertz(
square(CurrentRow,CurrentCol,[e])
),
NextCol is CurrentCol -1,
createCol(CurrentRow,NextCol).
maxBound(B) :- %
setof(Row,square(Row,_,_),L), % L = [1,2,3,4]
reverse(L,[B|_]). % L = [4,3,2,1] => B = 4
printBoard :-
maxBound(Bound),
setof([R,C,Contents],
square(R,C,Contents),Squares),
% Squares = [[1,1,[e]],[1,2,[e],....]
printSquares(Squares,Bound),nl.
printSquares([],_). % stop if we printed all the squares
printSquares(S,0) :- % Print New Row
maxBound(B),
nl,printSquares(S,B).
% Print a square that is revealed
% Squares = [[1,1,[e]] | [1,2,[e],....]
printSquares([[R,C,Contents]|Rest],ColCount) :-
show(L),
member([R,C],L),
extract([p,w],Contents,Display),
padd(Display,3,Padded),
write(Padded),
NewColCount is ColCount - 1,
printSquares(Rest,NewColCount).
% Print one that is not visible
printSquares([_|Rest],ColCount) :-
write('[----]'),
NewColCount is ColCount - 1,
printSquares(Rest,NewColCount).
extract([],L,L).
extract([H|T],L,FinalList) :-
delete(L,H,ReducedL),
% delete fails if H is not in the contents
extract(T,ReducedL,FinalList).
extract([_|T],L,FinalList) :-
extract(T,L,FinalList).
padd(L,Max,P) :-
length(L,Len),
paddout(L,Max,Len,P).
paddout(L,Max,Max,L).
paddout(L,Max,Len,[' '|P]) :-
Len1 is Len + 1,
paddout(L,Max,Len1,P).
% you can place a piece on a board of N size if you can generate a row and column value and you can place that piece on an square empty square
place(Piece,N) :-
Row1 is random(N),
Col1 is random(N),
place(Piece,Row1,Col1,N).
% you can place a pit if the square is empty at the specified
% position
place(p,Row,Col,_) :-
square(Row,Col,[e]),
retract(square(Row,Col,[e])),
assert(square(Row,Col,[p])).
% Find an Item at a position R,C by
% examining the contents of the R,C, location
find(R,C,Item) :-
square(R,C,Contents),
member(Item,Contents).
safe_square(Xa,Ya,X,Y) :-
maxBound(N),
adjacent(Xa,Ya,X,Y,N),
safe(X,Y),
move(Xa,Ya,X,Y),
retract(show(L)),
append([[X,Y]],L,NewL),
assert(show(NewL)).
safe_square(Xa,Ya,X,Y) :-
maxBound(N),
adjacent(Xa,Ya,X,Y,N),
glitter(X,Y),
move(Xa,Ya,X,Y),
retract(show(L)),
append([[X,Y]],L,NewL),
assert(show(NewL)).
safe_square(Xa,Ya,X,Y) :-
maxBound(N),
adjacent(Xa,Ya,X,Y,N),
glitter(X,Y),
move(Xa,Ya,X,Y),
retract(show(L)),
append([[X,Y]],L,NewL),
assert(show(NewL)).
safe_square(Xa,Ya,X,Y) :-
maxBound(N),
adjacent(Xa,Ya,X,Y,N),
empty(X,Y),
move(Xa,Ya,X,Y),
retract(show(L)),
append([[X,Y]],L,NewL),
assert(show(NewL)).
safe_square(Xa,Ya,X,Y) :-
maxBound(N),
adjacent(Xa,Ya,X,Y,N),
gold(X,Y),
move(Xa,Ya,X,Y),
retract(show(L)),
append([[X,Y]],L,NewL),
assert(show(NewL)).
move(Xa,Ya,X,Y) :-
retract(square(Xa,Ya,ListFrom)),
delete(ListFrom,a,Existing),
retract(square(X,Y,ListTo)),
append([a],ListTo,NextPositionList),
assert(square(Xa,Ya,Existing)),
assert(square(X,Y,NextPositionList)),
!.
safe(X,Y) :-
square(X,Y,L),
\+ member(p,L),
\+ member(w,L).
gold(X,Y) :-
square(X,Y,L),
member(x,L).
glitter(X,Y):-
square(X,Y,L),
member(g,L).
empty(X,Y):-
square(X,Y,L),
member(e,L).
adjacent(R,C,Ar,Ac,_) :- Ar is R -1, Ar >= 1, Ac is C.
adjacent(R,C,Ar,Ac,N) :- Ar is R + 1, Ar =< N, Ac is C.
adjacent(R,C,Ar,Ac,_) :- Ac is C - 1, Ac >= 1, Ar is R.
adjacent(R,C,Ar,Ac,N) :- Ac is C + 1, Ac =< N, Ar is R.
run:-
printBoard,
at(Xa,Ya,X,Y),
move(Xa,Ya,X,Y),
get0(_),
run.