Advent of Code 2019 - Day 6

KalvinHom · December 8, 2019, 8:50am

my solution
Did not use digraph, i just traversed the tree of SAN for distances, and then found YOU’s intersection with it.

simon · December 8, 2019, 8:15pm

Add me as someone else who didn’t use digraph and who just worked through lists (well maps) of planets. My solution is here.

ferd · December 9, 2019, 12:30am

Caught up partly today, my Day 6 video of using digraphs in Erlang:

michallepicki · December 9, 2019, 9:33pm

Catching up with Gleam, also using digraph: https://github.com/michallepicki/adventofcode/blob/master/2019/gleam/src/universal_orbit_map.gleam

edit: First time using digraph so I didn’t know get_short_path exists and implemented my own silly search

poligen · December 10, 2019, 8:24am

Thank you everyone here, this is my first time to understand algorithm about graph. And I am amazing about erlang’s standard documentation.

montanonic · December 19, 2019, 1:18am

Some great solutions here!

I didn’t know of digraph, and also used the --/2 operator instead of sets (first time I’ve used it, it’s nice!).

github.com

montanonic/advent2019_elxir/blob/master/lib/day6.ex

defmodule Day6 do
  def part1 do
    orbits = parse_orbits(data())

    orbits
    |> Map.keys()
    |> Enum.reduce(0, fn planet, count -> steps_to_center(orbits, planet) + count end)
  end

  def part2 do
    orbits = parse_orbits(data())

    you_orbit = orbits["YOU"]
    santa_orbit = orbits["SAN"]

    fewest_orbital_transfers_between_planets(orbits, you_orbit, santa_orbit)
  end

  def data, do: Advent2019.input_blob(__MODULE__)

This file has been truncated. show original