83 lines
1.7 KiB
Elixir
83 lines
1.7 KiB
Elixir
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defmodule Aoc.Solution.Day03 do
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import Aoc.Utils
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@name "Day 3: Rucksack Reorganization"
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@behaviour Solution
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@impl Solution
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def get_name, do: @name
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@impl Solution
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def present(solution), do: "Sum of priorities is #{solution}"
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@impl Solution
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def present_again(solution), do: "Sum of the unauthenticated priorities are #{solution}"
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@impl Solution
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def parse!(raw) do
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raw
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|> split_lines()
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end
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@impl Solution
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def solve(rucksacks) do
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rucksacks
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|> Enum.map(&compartment_pair/1)
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|> Enum.map(&calculate_compartment_priorities/1)
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|> Enum.sum()
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end
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@impl Solution
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def solve_again(rucksacks) do
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rucksacks
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|> Enum.chunk_every(3)
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|> Enum.map(&calculate_compartment_priorities/1)
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|> Enum.sum()
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end
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def compartment_pair(line) do
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half = line |> String.length() |> div(2)
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String.split_at(line, half)
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end
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def calculate_compartment_priorities(compartments) when is_tuple(compartments) do
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[a, b] =
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compartments
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|> Tuple.to_list()
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|> Enum.map(&distinct/1)
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common_priority(a, b)
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end
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def calculate_compartment_priorities(compartments) do
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[a, b, c] =
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compartments
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|> Enum.map(&distinct/1)
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common_priority(a, b, c)
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end
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def distinct(line) do
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line |> String.codepoints() |> MapSet.new()
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end
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def priority(char) when is_binary(char), do: char |> String.to_charlist() |> hd |> priority
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def priority(n) when n > 96, do: n - 96
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def priority(n), do: n - 38
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def common_priority(a, b, c) do
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MapSet.intersection(a, b)
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|> MapSet.intersection(c)
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|> MapSet.to_list()
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|> List.first()
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|> priority
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end
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def common_priority(a, b) do
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MapSet.intersection(a, b)
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|> MapSet.to_list()
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|> List.first()
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|> priority
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end
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end
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