:- use_module(library(lists),[member/2]).
:- use_module(contestlib,[sublist/2, for/3]).

mamadee(MazeSize,Entry,Exit,MaxWalls,Walls,Blocking) :-
	for(I,1,MaxWalls),
	length(Blocking,I),
	sublist(Walls,Blocking),
	Been = [Entry],
	\+ exists_path(Entry,Exit,MazeSize,Been,Blocking),
	!.

exists_path(Entry,Exit,MazeSize,Been,Blocking) :-
	( Exit == Entry ->
	    true
	;
	    step(Entry,NewEntry,MazeSize,Blocking),
	    \+ member(NewEntry,Been),
	    exists_path(NewEntry,Exit,MazeSize,[NewEntry|Been],Blocking)
	).

step((A,B),(X,Y),MazeSize,Blocking) :-
	(
	  X = A, Y is B + 1,
	  C is A - 1, D = B,
	  U = A, V = B
	  
	;
	  X = A, Y is B - 1,
	  C is X - 1, D = Y,
	  U = X, V = Y
	;
	  Y = B, X is A + 1,
	  C = A, D is B - 1,
	  U = A, V = B
	;
	  Y = B, X is A - 1,
	  C = X, D is Y - 1,
	  U = X, V = Y
	),
	1 =< X, X =< MazeSize, 
	1 =< Y, Y =< MazeSize,
	\+ member(wall((C,D),(U,V)),Blocking),
	\+ member(wall((U,V),(C,D)),Blocking).