56 lines
1.5 KiB
Elixir
56 lines
1.5 KiB
Elixir
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defmodule Day04 do
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use Application
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def start(_type, _args) do
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input = File.read!("./input.txt")
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IO.puts "Part 1: " <> to_string(part1(input))
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IO.puts "Part 2: " <> to_string(part2(input))
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Supervisor.start_link [], strategy: :one_for_one
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end
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def part1(input) do
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input |> String.split("\n") |> Enum.map(&line_part1/1) |> Enum.sum
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end
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def part2(input) do
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card_values = input |> String.split("\n") |> Enum.map(&line_part2/1)
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card_amounts_initial = Enum.map(card_values, fn _ -> 1 end) |> Enum.with_index
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card_amounts_processed = Enum.reduce(Enum.map(card_amounts_initial, fn {_, i} -> i end), card_amounts_initial, fn i, acc ->
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{cur, _} = Enum.fetch!(acc, i)
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value = Enum.fetch!(card_values, i)
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Enum.map(acc, fn {cur2, i2} ->
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if value > 0 and i2 in (i+1)..(i+value) do
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{cur2 + cur, i2}
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else
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{cur2, i2}
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end
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end)
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end)
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card_amounts_processed |> Enum.map(fn {x, _} -> x end) |> Enum.sum
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end
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def line_part1(input) do
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[_, numbers] = String.split(input, ": ")
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[winning, own] = String.split(numbers, " | ") |> Enum.map(&String.split/1)
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matching = Enum.map(own, &(&1 in winning)) |> Enum.count(&(&1))
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if matching > 0 do
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:math.pow(2, matching - 1) |> round
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else
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0
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end
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end
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def line_part2(input) do
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[_, numbers] = String.split(input, ": ")
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[winning, own] = String.split(numbers, " | ") |> Enum.map(&String.split/1)
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Enum.map(own, &(&1 in winning)) |> Enum.count(&(&1))
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end
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end
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