hauleth.dev
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Day 06
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2023/day06.livemd
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2023/day06.livemd
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<!-- livebook:{"persist_outputs":true} -->
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# Day 06
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```elixir
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Mix.install([:kino_aoc])
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```
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## Section
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<!-- livebook:{"attrs":{"assign_to":"puzzle_input","day":"6","session_secret":"ADVENT_OF_CODE_SESSION","year":"2023"},"chunks":null,"kind":"Elixir.KinoAOC.HelperCell","livebook_object":"smart_cell"} -->
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```elixir
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{:ok, puzzle_input} =
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KinoAOC.download_puzzle("2023", "6", System.fetch_env!("LB_ADVENT_OF_CODE_SESSION"))
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```
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<!-- livebook:{"output":true} -->
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```
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{:ok, "Time: 44 80 65 72\nDistance: 208 1581 1050 1102"}
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```
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```elixir
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# puzzle_input =
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"""
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Time: 7 15 30
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Distance: 9 40 200
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"""
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|> String.trim()
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```
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<!-- livebook:{"output":true} -->
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```
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"Time: 7 15 30\nDistance: 9 40 200"
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```
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```elixir
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defmodule Day06 do
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def solve(t, d) do
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delta = t ** 2 - 4 * d
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sq_delta = :math.sqrt(delta)
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diff = if sq_delta == floor(sq_delta), do: 1, else: 0
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x1 = (-t + sq_delta) / -2
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x2 = (-t - sq_delta) / -2
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ceil(x2) - ceil(x1) - diff
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end
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end
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```
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<!-- livebook:{"output":true} -->
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```
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{:module, Day06, <<70, 79, 82, 49, 0, 0, 8, ...>>, {:solve, 2}}
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```
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## Part 1
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```elixir
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puzzle_input
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|> String.split("\n")
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|> Enum.map(fn line ->
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line
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|> String.split(" ", trim: true)
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|> tl()
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|> Enum.map(&String.to_integer/1)
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end)
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|> Enum.zip()
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|> Enum.map(fn {t, d} -> Day06.solve(t, d) end)
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|> Enum.product()
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```
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<!-- livebook:{"output":true} -->
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```
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32076
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```
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## Part 2
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```elixir
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[t, d] =
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puzzle_input
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|> String.split("\n")
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|> Enum.map(fn line ->
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line
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|> String.split(" ", trim: true)
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|> tl()
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|> Enum.join()
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|> String.to_integer()
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end)
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Day06.solve(t, d)
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```
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<!-- livebook:{"output":true} -->
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```
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34278221
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```
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<!-- livebook:{"offset":1728,"stamp":{"token":"XCP.RVwRJJq0k3Evn9IAmQDOmuVfBQ2xs0pbIqwAVIMLYEO8Olj2RUttefJ6ky9G2BD-EzyDh-ZjERuBL8PVkFPkYz8g7hdsY0keFA-TEIL4GC3n2j_IwPT1JHFDQ0FwiPBw5g","version":2}} -->