day21.erl

%%% @doc
%%% welcome to day twenty-one, where dreams come true
%%% but all kinds of weird like a monkey paw thing
%%% @end
-module(day21).
-export([p1/0, p2/0]).

%% AND X Y
%% OR X Y
%% NOT X Y
%% where Y is writeable
%%
%% A: 1 ahead
%% B: 2 ahead
%% C: 3 ahead
%% D: 4 ahead
%% T: temporary (false at first)
%% J: jump according to last value (false at first)
%% ABCD: true if ground, false if hole
%% EFGHI: like ABCD, but in RUN mode
%% all jumps land on D (4th tile)
p1() ->
    Program = intcode:parse_program(advent:input("day21")),
    Pid = intcode:spawn_program(Program, self()),
    Script =
        "NOT A J\n"
        "NOT B T\n"
        "OR T J\n"
        "NOT C T\n"
        "OR T J\n"
        "AND D J\n",
    intcode:send_string(Pid, Script),
    intcode:send_string(Pid, "WALK\n"),
    _ = intcode:collect_result(Pid),
    lists:last(intcode:collect_io()).
    %io:format("~s~n", [intcode:collect_io()]).

p2() ->
    Program = intcode:parse_program(advent:input("day21")),
    Pid = intcode:spawn_program(Program, self()),
    %%   @
    %% #####.#.#...##### D H = avail + holes in A-C
    %%    ABCDEFGHI
    %%     @
    %% #####...####..### D (E|H) avail + holes in A-C
    %%      ABCDEFGHI
    Script =
        "NOT A T\n"
        "NOT B J\n"
        "OR T J\n" % hole in A/B in J
        "NOT C T\n"
        "OR T J\n" % hole in A/B/C in J
        "AND D J\n"% D must be free
        "NOT J T\n" % if J is true, then T's false; if J is false, it doesn't matter what T is
        "OR E T\n"
        "OR H T\n"
        "AND T J\n",
    intcode:send_string(Pid, Script),
    intcode:send_string(Pid, "RUN\n"),
    _ = intcode:collect_result(Pid),
    lists:last(intcode:collect_io()).