Day 7: The Sum of Its Parts - Advent of Code 2018
I did the Advent of Code 2018 day 7 challenge in Elixir! Parts one and two are as follows:
defmodule Day7 do
@instruction_info ~r/Step (\w+) must be finished before step (\w+) can begin/
def part1(input) do
input
|> read_input()
|> parse_input()
|> discover_dependencies([])
end
defp read_input(input) do
input
|> File.read!()
|> String.split("\n", trim: true)
end
defp parse_input(lines) do
Enum.reduce(lines, %{}, fn line, acc ->
[step, dependency] = Regex.run(@instruction_info, line, capture: :all_but_first)
acc
|> Map.put_new(step, [])
|> Map.update(dependency, [step], fn dependencies ->
Enum.sort([step | dependencies])
end)
end)
|> Enum.to_list()
end
defp discover_dependencies(deps_tree, acc) when map_size(deps_tree) == 0do
acc |> Enum.reverse() |> Enum.join()
end
defp discover_dependencies(deps_tree, acc) do
{step, []} = Enum.find(deps_tree, fn {_, deps} -> Enum.empty?(deps) end)
new_dependencies =
Enum.reduce(deps_tree, %{}, fn
{^step, _}, acc -> Map.delete(acc, step)
{other_step, deps}, acc -> Map.put_new(acc, other_step, List.delete(deps, step))
end)
discover_dependencies(new_dependencies, [step | acc])
end
end
# r Day7; :aoc2018 |> :code.priv_dir() |> Path.join("day7.txt") |> Day7.part1()
# :aoc2018 |> :code.priv_dir() |> Path.join("day7.txt") |> Day7.part2()
input = "Step D must be finished before step E can begin.
Step F must be finished before step E can begin.
Step C must be finished before step A can begin.
Step B must be finished before step E can begin.
Step A must be finished before step D can begin.
Step C must be finished before step F can begin.
Step A must be finished before step B can begin."
# r Day7; Day7.part1(input)
![Simon Escobar Benitez](/uploads/media/speakers/0001/01/thumb_722_speakers_small.png)
ARTICLES: 8
Day 11: Chronal Charge - Advent of Code 2018
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I did the Advent of Code 2018 day 11 challenge in Elixir! Parts one and two are as follows:
READ MOREDay 10: The Stars Align - Advent of Code 2018
![Day 10: The Stars Align - Advent of Code 2018](/uploads/media/articles/0001/01/450f1697974651b50d74fce5f03b2bed0fead382.png)
I did the Advent of Code 2018 day 10 challenge in Elixir! Parts one and two are as follows:
READ MOREDay 6: Chronal Coordinates - Advent of Code 2018
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I did the Advent of Code 2018 day 6 challenge in Elixir! Parts one and two are as follows:
READ MOREDay 5: Alchemical Reduction - Advent of Code 2018
![Day 5: Alchemical Reduction - Advent of Code 2018](/uploads/media/articles/0001/01/4609e59fb2d556c4657bd52aea2a991dcd59a1f1.png)
I did the Advent of Code 2018 day 5 challenge in Elixir! Parts one and two are as follows:
READ MOREDay 4: Repose Record - Advent of Code 2018
![Day 4: Repose Record - Advent of Code 2018](/uploads/media/articles/0001/01/3996c8b8f765c5d1a0485e3bc309863d97427109.png)
I did the Advent of Code 2018 day 4 challenge in Elixir! Parts one and two are as follows:
READ MOREDay 3: No matter how you slice it - Advent of Code 2018
![Day 3: No matter how you slice it - Advent of Code 2018](/uploads/media/articles/0001/01/c4cdaaaaa6fbfc6d3be78ddcbe2f05bf8ccea64f.png)
I did the Advent of Code 2018 day 3 challenge in Elixir! Parts one and two are as follows:
READ MOREDay 2: Inventory Management System - Advent of Code 2018
![Day 2: Inventory Management System - Advent of Code 2018](/uploads/media/articles/0001/01/10a67edefbec721abd6940f0b4990adfc8683a1d.png)
I did the Advent of Code 2018 day 2 challenge in Elixir! Parts one and two are as follows:
READ MOREDay 1: Chronal Calibration - Advent of Code 2018
![Day 1: Chronal Calibration - Advent of Code 2018](/uploads/media/articles/0001/01/007cb411da7da99ec16de318f4062c00930db5cd.png)
Advent of Code 2018 - Day 1 solution in Elixir! #AdventOfBEAM
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