43 lines
1.1 KiB
Elixir
43 lines
1.1 KiB
Elixir
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defmodule AOC.Day5 do
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@upper 'BR'
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@lower 'FL'
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def search_range([], x, x), do: x
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def search_range([hd | tl], low, high) when hd in @lower do
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search_range(tl, low, div(high + 1 + low, 2) - 1)
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end
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def search_range([hd | tl], low, high) when hd in @upper do
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search_range(tl, div(low + high + 1, 2), high)
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end
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def search_seat({row_search, col_search}) do
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row = search_range(row_search, 0, 127)
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column = search_range(col_search, 0, 7)
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{row, column}
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end
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def part1 do
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AOC.Util.input_lines(5, 1)
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|> Enum.map(&String.to_charlist/1)
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|> Enum.map(&Enum.split(&1, 7))
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|> Enum.map(&search_seat/1)
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|> Enum.map(fn {r, c} -> r * 8 + c end)
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|> Enum.max()
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end
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def find_missing_seat([l, r | _]) when r != l + 1, do: l + 1
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def find_missing_seat([_ | tl]), do: find_missing_seat(tl)
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def part2 do
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AOC.Util.input_lines(5, 1)
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|> Enum.map(&String.to_charlist/1)
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|> Enum.map(&Enum.split(&1, 7))
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|> Enum.map(&search_seat/1)
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|> Enum.map(fn {r, c} -> r * 8 + c end)
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|> Enum.sort()
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|> find_missing_seat()
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end
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end
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