70 lines
2.1 KiB
Erlang
70 lines
2.1 KiB
Erlang
-module(day_3).
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-export([part_1/0, part_2/0]).
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-export([parse/1]).
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%% mul\((\d{1,3}),(\d{1,3})\)
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part_1() ->
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Filename = filename:absname("./priv/input/3.txt"),
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part_1(Filename).
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part_1(Filename) ->
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Input = read_input(Filename),
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Pairs = parse(Input),
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io:format("~p~n", [Pairs]),
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Products = lists:map(fun({A, B}) -> A * B end, Pairs),
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lists:sum(Products).
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part_2() ->
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Filename = filename:absname("./priv/input/3.txt"),
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part_2(Filename).
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part_2(Filename) ->
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Input = read_input(Filename),
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0.
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%% Private Functions
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read_input(Filename) ->
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{ok, Binary} = file:read_file(Filename),
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Binary.
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parse(Binary) ->
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parse(Binary, []).
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parse(<<"mul(",A:1/binary,",",B:1/binary,")",Rest/binary>>, Pairs) -> parse(Rest, [make_pair(A, B) | Pairs]);
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parse(<<"mul(",A:1/binary,",",B:2/binary,")",Rest/binary>>, Pairs) -> parse(Rest, [make_pair(A, B) | Pairs]);
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parse(<<"mul(",A:1/binary,",",B:3/binary,")",Rest/binary>>, Pairs) -> parse(Rest, [make_pair(A, B) | Pairs]);
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parse(<<"mul(",A:2/binary,",",B:1/binary,")",Rest/binary>>, Pairs) -> parse(Rest, [make_pair(A, B) | Pairs]);
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parse(<<"mul(",A:2/binary,",",B:2/binary,")",Rest/binary>>, Pairs) -> parse(Rest, [make_pair(A, B) | Pairs]);
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parse(<<"mul(",A:2/binary,",",B:3/binary,")",Rest/binary>>, Pairs) -> parse(Rest, [make_pair(A, B) | Pairs]);
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parse(<<"mul(",A:3/binary,",",B:1/binary,")",Rest/binary>>, Pairs) -> parse(Rest, [make_pair(A, B) | Pairs]);
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parse(<<"mul(",A:3/binary,",",B:2/binary,")",Rest/binary>>, Pairs) -> parse(Rest, [make_pair(A, B) | Pairs]);
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parse(<<"mul(",A:3/binary,",",B:3/binary,")",Rest/binary>>, Pairs) -> parse(Rest, [make_pair(A, B) | Pairs]);
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parse(<<_:8,Rest/binary>>, Pairs) ->
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parse(Rest, Pairs);
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parse(<<_Whatever:8>>, Pairs) ->
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Pairs;
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parse(<<"">>, Pairs) ->
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Pairs.
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make_pair(A, B) -> {binary_to_integer(A), binary_to_integer(B)}.
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%% TESTS
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-ifdef(TEST).
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-include_lib("eunit/include/eunit.hrl").
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part_1_test() ->
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TestFile = test_data(),
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?assertEqual(161, part_1(TestFile)).
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%% part_2_test() ->
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%% TestFile = test_data(),
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%% ?assertEqual(4, part_2(TestFile)).
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test_data() ->
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filename:absname("./priv/test_input/3.txt").
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-endif.
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