day18 solution

day18/Makefile

@@ -0,0 +1,8 @@
+all: day18.beam
+	erl -noshell -s day18 start -s init stop
+
+day18.beam:
+	erlc day18.erl
+
+clean:
+	rm -f day18.beam

day18/day18.erl

@@ -0,0 +1,174 @@
+-module(day18).
+-export([start/0]).
+
+value_or_register(X, Registers)
+  when X >= <<"a">>, X =< <<"z">> -> maps:get(X, Registers, 0);
+value_or_register(X, _Registers)
+  -> { NewValue, _ } = string:to_integer(X),
+     NewValue.
+
+assemble(Input)
+  -> Instructions = lists:map(fun(X) -> [A|Args] = re:split(X, " "), { A, Args } end, re:split(Input, "\n")),
+     assemble(Instructions, length(Instructions), 1, 0, maps:new()).
+
+assemble(_Instructions, MaxInstructions, Ip, LastFrequency, _Registers)
+  when Ip < 1; Ip > MaxInstructions -> LastFrequency;
+assemble(Instructions, MaxInstructions, Ip, LastFrequency, Registers)
+  -> { Op, Args } = lists:nth(Ip, Instructions),
+     case Op of
+       <<"add">> ->
+         [Src,Dest|_] = Args,
+         ExistingValue = maps:get(Src, Registers, 0),
+         NewValue = value_or_register(Dest, Registers),
+         assemble(Instructions, MaxInstructions, Ip + 1, LastFrequency, maps:put(Src, ExistingValue + NewValue, Registers));
+       <<"jgz">> ->
+         [Src,Dest|_] = Args,
+         NewValue = value_or_register(Dest, Registers),
+         RegisterValue = maps:get(Src, Registers, 0),
+         if RegisterValue > 0 -> assemble(Instructions, MaxInstructions, Ip + NewValue, LastFrequency, Registers);
+            true -> assemble(Instructions, MaxInstructions, Ip + 1, LastFrequency, Registers)
+         end;
+       <<"mod">> ->
+         [Src,Dest|_] = Args,
+         ExistingValue = maps:get(Src, Registers, 0),
+         NewValue = value_or_register(Dest, Registers),
+         assemble(Instructions, MaxInstructions, Ip + 1, LastFrequency, maps:put(Src, ExistingValue rem NewValue, Registers));
+       <<"mul">> ->
+         [Src,Dest|_] = Args,
+         ExistingValue = maps:get(Src, Registers, 0),
+         NewValue = value_or_register(Dest, Registers),
+         assemble(Instructions, MaxInstructions, Ip + 1, LastFrequency, maps:put(Src, ExistingValue * NewValue, Registers));
+       <<"rcv">> ->
+         [Dest|_] = Args,
+         NewValue = value_or_register(Dest, Registers),
+         if NewValue /= 0 -> LastFrequency;
+            true -> assemble(Instructions, MaxInstructions, Ip + 1, LastFrequency, Registers)
+         end;
+       <<"set">> ->
+         [Src,Dest|_] = Args,
+         NewValue = value_or_register(Dest, Registers),
+         assemble(Instructions, MaxInstructions, Ip + 1, LastFrequency, maps:put(Src, NewValue, Registers));
+       <<"snd">> ->
+         [Dest|_] = Args,
+         NewValue = value_or_register(Dest, Registers),
+         assemble(Instructions, MaxInstructions, Ip + 1, NewValue, Registers)
+    end.
+
+assemble2(Input)
+  -> Instructions = lists:map(fun(X) -> [A|Args] = re:split(X, " "), { A, Args } end, re:split(Input, "\n")),
+     assemble2(Instructions, length(Instructions), 1, maps:put(<<"p">>, 0, maps:new()), [], 0, 1, maps:put(<<"p">>, 1, maps:new()), []).
+
+assemble2(Instructions, MaxInstructions, Ip0, Registers0, Queue0, SndCount, Ip1, Registers1, Queue1)
+  -> { NewIp0, NewRegisters0, NewQueue0, NewQueue1, _ } = assemble3(Instructions, MaxInstructions, Ip0, Registers0, Queue0, Queue1),
+     { NewIp1, NewRegisters1, AnotherNewQueue1, AnotherNewQueue0, Count } = assemble3(Instructions, MaxInstructions, Ip1, Registers1, NewQueue1, NewQueue0),
+     NewSndCount = SndCount + Count,
+     %io:fwrite("newsndcount ~p~n", [NewSndCount]),
+     %io:fwrite("ip0 ~p ip1 ~p~nq0 ~p~nq1 ~p~n", [NewIp0, NewIp1, AnotherNewQueue0, AnotherNewQueue1]),
+     if Ip0 == NewIp0, Ip1 == NewIp1 -> NewSndCount;
+        true -> assemble2(Instructions, MaxInstructions, NewIp0, NewRegisters0, AnotherNewQueue0, NewSndCount, NewIp1, NewRegisters1, AnotherNewQueue1)
+     end.
+
+assemble3(_Instructions, MaxInstructions, Ip, Registers, Queue, OtherQueue)
+  when Ip < 1; Ip > MaxInstructions -> { Ip, Registers, Queue, OtherQueue, 0 };
+assemble3(Instructions, _MaxInstructions, Ip, Registers, Queue, OtherQueue)
+  -> { Op, Args } = lists:nth(Ip, Instructions),
+     case Op of
+       <<"add">> ->
+         [Src,Dest|_] = Args,
+         ExistingValue = maps:get(Src, Registers, 0),
+         NewValue = value_or_register(Dest, Registers),
+         { Ip + 1, maps:put(Src, ExistingValue + NewValue, Registers), Queue, OtherQueue, 0 };
+       <<"jgz">> ->
+         [Src,Dest|_] = Args,
+         SrcValue = value_or_register(Src, Registers),
+         NewValue = value_or_register(Dest, Registers),
+         if SrcValue > 0 -> { Ip + NewValue, Registers, Queue, OtherQueue, 0 };
+            true -> { Ip + 1, Registers, Queue, OtherQueue, 0 }
+         end;
+       <<"mod">> ->
+         [Src,Dest|_] = Args,
+         ExistingValue = maps:get(Src, Registers, 0),
+         NewValue = value_or_register(Dest, Registers),
+         { Ip + 1, maps:put(Src, (ExistingValue rem NewValue), Registers), Queue, OtherQueue, 0 };
+       <<"mul">> ->
+         [Src,Dest|_] = Args,
+         ExistingValue = maps:get(Src, Registers, 0),
+         NewValue = value_or_register(Dest, Registers),
+         { Ip + 1, maps:put(Src, (ExistingValue * NewValue), Registers), Queue, OtherQueue, 0 };
+       <<"rcv">> ->
+         [Dest|_] = Args,
+         QueueLen = length(Queue),
+         if QueueLen == 0 -> { Ip, Registers, Queue, OtherQueue, 0 };
+            true -> [Head|Tail] = Queue, { Ip + 1, maps:put(Dest, Head, Registers), Tail, OtherQueue, 0 }
+         end;
+       <<"set">> ->
+         [Src,Dest|_] = Args,
+         NewValue = value_or_register(Dest, Registers),
+         { Ip + 1, maps:put(Src, NewValue, Registers), Queue, OtherQueue, 0 };
+       <<"snd">> ->
+         [Dest|_] = Args,
+         NewValue = value_or_register(Dest, Registers),
+         { Ip + 1, Registers, Queue, lists:append(OtherQueue, [NewValue]), 1 }
+    end.
+
+start()
+  -> io:fwrite("~p~n", [ assemble("set a 1
+add a 2
+mul a a
+mod a 5
+snd a
+set a 0
+rcv a
+jgz a -1
+set a 1
+jgz a -2") ]),
+     Instructions = "set i 31
+set a 1
+mul p 17
+jgz p p
+mul a 2
+add i -1
+jgz i -2
+add a -1
+set i 127
+set p 952
+mul p 8505
+mod p a
+mul p 129749
+add p 12345
+mod p a
+set b p
+mod b 10000
+snd b
+add i -1
+jgz i -9
+jgz a 3
+rcv b
+jgz b -1
+set f 0
+set i 126
+rcv a
+rcv b
+set p a
+mul p -1
+add p b
+jgz p 4
+snd a
+set a b
+jgz 1 3
+snd b
+set f 1
+add i -1
+jgz i -11
+snd a
+jgz f -16
+jgz a -19",
+     io:fwrite("~p~n", [ assemble(Instructions) ]),
+     io:fwrite("~p~n", [ assemble2("snd 1
+snd 2
+snd p
+rcv a
+rcv b
+rcv c
+rcv d") ]),
+     io:fwrite("~p~n", [ assemble2(Instructions) ]).