Day 5: If You Give a Seed a Fertilizer


Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
  • Code block support is not fully rolled out yet but likely will be in the middle of the event. Try to share solutions as both code blocks and using something such as https://topaz.github.io/paste/ , pastebin, or github (code blocks to future proof it for when 0.19 comes out and since code blocks currently function in some apps and some instances as well if they are running a 0.19 beta)

FAQ


🔒This post will be unlocked when there is a decent amount of submissions on the leaderboard to avoid cheating for top spots

🔓 Unlocked after 27 mins (current record for time, hard one today)

  • hades@lemm.ee
    link
    fedilink
    arrow-up
    2
    ·
    11 months ago

    Python

    Questions and feedback welcome!

    import portion as P
    
    from .solver import Solver
    
    _maps = [
      'seed-to-soil',
      'soil-to-fertilizer',
      'fertilizer-to-water',
      'water-to-light',
      'light-to-temperature',
      'temperature-to-humidity',
      'humidity-to-location',
    ]
    
    def group_lines_in_maps(lines):
      group = []
      for line in lines:
        if not line:
          yield group
          group = []
          continue
        group.append(line)
      yield group
    
    class Day05(Solver):
      def __init__(self):
        super().__init__(5)
        self.seeds = []
        self.mappings = {}
    
      def presolve(self, input: str):
        lines = input.rstrip().split('\n')
        self.seeds = list(map(int, lines[0].split(' ')[1:]))
        self.mappings = {}
        for mapping in group_lines_in_maps(lines[2:]):
          mapping_name = mapping[0].split(' ')[0]
          mapping_ranges = map(lambda rng: tuple(map(int, rng.split(' '))), mapping[1:])
          self.mappings[mapping_name] = list(mapping_ranges)
    
    
      def solve_first_star(self):
        locations = []
        for seed in self.seeds:
          location = seed
          for mapping in map(self.mappings.get, _maps):
            assert mapping
            for dest, source, length in mapping:
              if 0 <= location - source < length:
                location = dest + (location - source)
                break
          locations.append(location)
        return min(locations)
    
    
      def solve_second_star(self):
        current_set = P.empty()
        for i in range(0, len(self.seeds), 2):
          current_set = current_set | P.closedopen(self.seeds[i], self.seeds[i] + self.seeds[i + 1])
        for mapping in map(self.mappings.get, _maps):
          assert mapping
          unmapped = current_set
          next_set = P.empty()
          for dest, source, length in mapping:
            delta = dest - source
            source_range = P.closedopen(source, source + length)
            mappable = unmapped & source_range
            mapped_to_destination = mappable.apply(
                lambda x: (x.left, x.lower + delta, x.upper + delta, x.right))  # pylint: disable=cell-var-from-loop
            next_set = next_set | mapped_to_destination
            unmapped = unmapped - source_range
          current_set = next_set | unmapped
        return next(P.iterate(current_set, step=1))