Advent of Code Solutions
advent-of-code
aoc
2015: Day 1
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.gitignore
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.gitignore
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input-real
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2015/01/solution.erl
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2015/01/solution.erl
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#!/usr/bin/env escript
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% --- Part 1 Code
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part1(Input) ->
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io:format("Part 1: ~b~n", [destination(0, Input)]).
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destination(Floor, Input) ->
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case {_, Rest} = next_char(Input) of
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{"(", _} -> destination(Floor + 1, Rest);
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{")", _} -> destination(Floor - 1, Rest);
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{"\n", _} -> Floor
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end.
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% --- Part 2 Code
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part2(Input) ->
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io:format("Part 2: ~b~n", [basement_enter(0, 0, Input)]).
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basement_enter(Position, Floor, Input) ->
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if
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Floor == -1 ->
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Position;
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true ->
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case {_, Rest} = next_char(Input) of
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{"(", _} -> basement_enter(Position + 1, Floor + 1, Rest);
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{")", _} -> basement_enter(Position + 1, Floor - 1, Rest);
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{"\n", _} -> halt(1) % If we get here, our puzzle input is impossible
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end
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end.
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% --- Generic Helper Functions
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next_char([Char | String]) -> {[Char], String}.
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read_input() -> read_input("").
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read_input(PrevLine) ->
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case io:get_chars("", 8192) of
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eof -> PrevLine;
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Data -> read_input(PrevLine ++ Data)
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end.
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main(Args) ->
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Input = read_input(),
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case Args of
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["1"] ->
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part1(Input);
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["2"] ->
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part2(Input);
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_ ->
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part1(Input),
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part2(Input)
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end.