36 lines
692 B
Elixir
36 lines
692 B
Elixir
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defmodule Aoc.Solution.Day04 do
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@name "Day 4: The Ideal Stocking Stuffer"
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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 parse!(raw) do
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String.trim(raw)
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end
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@impl Solution
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def solve_first_part(input) do
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find_number(input, 0, "00000")
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end
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@impl Solution
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def solve_second_part(input) do
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find_number(input, 0, "000000")
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end
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defp find_number(a, b, prefix) do
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case valid_checksum?(a, b, prefix) do
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true -> b
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false -> find_number(a, b + 1, prefix)
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end
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end
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defp valid_checksum?(a, b, prefix) do
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:crypto.hash(:md5, "#{a}#{b}")
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|> Base.encode16()
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|> String.starts_with?(prefix)
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end
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end
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