73 lines
2.0 KiB
Elixir
73 lines
2.0 KiB
Elixir
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defmodule AdventOfCode.Day03 do
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def part1() do
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input = File.read!("./priv/day03.part1.txt")
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regex = ~r/mul\((\d{1,3}),(\d{1,3})\)/
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instructions = Regex.scan(regex, input)
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Enum.reduce(instructions, 0, fn instruction, sum ->
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[_, left, right] = instruction
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left = String.to_integer(left)
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right = String.to_integer(right)
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sum + left * right
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end)
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end
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def part2() do
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input = File.read!("./priv/day03.part2.txt")
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String.graphemes(input)
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|> Enum.with_index()
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|> Enum.reduce({0, true}, fn {letter, index}, {sum, enable_instruction} ->
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case letter do
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"m" ->
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{_head, substr} = String.split_at(input, index)
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case :binary.match(substr, ")") do
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{position, _length} ->
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instruction = String.slice(substr, 0, position + 1)
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case String.length(instruction) <= 12 and
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Regex.scan(~r/mul\((\d{1,3}),(\d{1,3})\)/, instruction) do
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[[_, left, right]] ->
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left = String.to_integer(left)
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right = String.to_integer(right)
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IO.inspect(instruction)
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IO.inspect(left)
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IO.inspect(right)
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IO.inspect(enable_instruction)
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case enable_instruction do
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true ->
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{sum + left * right, enable_instruction}
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false ->
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{sum, enable_instruction}
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end
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_ ->
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{sum, enable_instruction}
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end
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:nomatch ->
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{sum, enable_instruction}
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end
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"d" ->
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substr = String.slice(input, index, String.length("don't()"))
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cond do
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substr == "don't()" ->
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{sum, false}
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String.starts_with?(substr, "do()") ->
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{sum, true}
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end
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_ ->
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{sum, enable_instruction}
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end
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end)
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end
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end
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