Day 5-2

day5.erl

@@ -1,27 +1,26 @@
 -module(day5).
 
--compile(export_all).
 -export([solve/1]).
 
-
 solve(InputData) ->
 	[DiagramData, Instructions] = binary:split(InputData, <<"\n\n">>, [trim_all]),
 	Diagram = lists:reverse(binary:split(DiagramData, <<"\n">>, [trim_all, global])),
 	Stacks = parse_diagram(Diagram),
-	EndStacks = eval_instructions(Instructions, Stacks),
-	{print_stacks(EndStacks), none}.
+	EndStacks = eval_instructions(Instructions, Stacks, fun eval_move/4),
+	EndStacks2 = eval_instructions(Instructions, Stacks, fun eval_move2/4),
+	{print_stacks(EndStacks), print_stacks(EndStacks2)}.
 
 print_stacks(Stacks) ->
 	lists:reverse(
 	  maps:fold(fun (_Key, [Top|_Rest], Acc) -> [Top|Acc] end, [], Stacks)
 	 ).
 
-eval_instructions(<<>>, Stacks) -> Stacks;
-eval_instructions(Instructions, Stacks) ->
+eval_instructions(<<>>, Stacks, _MoveFun) -> Stacks;
+eval_instructions(Instructions, Stacks, MoveFun) ->
 	<<"move ", Instruction1/binary>> = Instructions,
 	{Moves, Instruction2} = parse_int(Instruction1),
 	<<" from ", DigitFrom, " to ", DigitTo, $\n, Rest/binary>> = Instruction2,
-	eval_instructions(Rest, eval_move(DigitFrom, DigitTo, Moves, Stacks)).
+	eval_instructions(Rest, MoveFun(DigitFrom, DigitTo, Moves, Stacks), MoveFun).
 	
 parse_int(String) -> parse_int(String, 0).
 parse_int(<<Char, Rest/binary>>, Acc) when Char >= $0 andalso Char =< $9 -> parse_int(Rest, Acc*10+(Char - $0));
@@ -32,6 +31,12 @@ eval_move(DigitFrom, DigitTo, N, Stacks) when is_integer(N) and (N > 0) ->
 	#{DigitFrom := [Item | StackFrom], DigitTo := StackTo} = Stacks,
 	eval_move(DigitFrom, DigitTo, N-1, Stacks#{DigitFrom := StackFrom, DigitTo := [Item | StackTo]}).
 
+eval_move2(DigitFrom, DigitTo, N, Stacks) when is_integer(N) and (N > 0) ->
+	#{DigitFrom := StackFrom, DigitTo := StackTo} = Stacks,
+	{Items, NewFrom} = lists:split(N, StackFrom),
+	NewTo = Items ++ StackTo,
+	Stacks#{DigitFrom := NewFrom, DigitTo := NewTo}.
+
 parse_diagram([Program | Boxes]) -> parse_diagram(Program, Boxes, #{}).
 
 parse_diagram(<<>>, _Boxes, Stacks) -> Stacks;