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defmodule Day2 do
def input() do
File.stream!("input/day2.in")
|> Stream.map(&String.trim/1)
end
def find_subcount(count) do
input()
|> Enum.reduce(0, fn x, acc ->
if x
|> String.graphemes()
|> Enum.sort()
|> Enum.uniq()
|> Enum.any?(fn y ->
Enum.count(String.graphemes(x), &(&1 == y)) == count
end) do
acc + 1
else
acc
end
end)
end
def find_common_chars() do
input()
|> Enum.reduce(%MapSet{}, fn x, acc ->
x
|> String.graphemes()
|> Enum.with_index()
|> Enum.reduce(acc, fn {_c, i}, seen ->
pair = {i, String.slice(x, 0, i) <> String.slice(x, (i + 1)..-1)}
if MapSet.member?(seen, pair), do: IO.puts(elem(pair, 1))
MapSet.put(seen, pair)
end)
end)
end
end
IO.puts(Day2.find_subcount(2) * Day2.find_subcount(3))
Day2.find_common_chars()
|
