Advent Of Code

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An unofficial home for the advent of code community on programming.dev!

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

AoC 2023

Solution Threads

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18	19	20	21	22	23	24
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console.log('Hello World')

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☃️ - 2023 DAY 4 SOLUTIONS -☃️ (programming.dev)

submitted 11 months ago* (last edited 11 months ago) by Ategon@programming.dev to c/advent_of_code@programming.dev

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Day 4: Scratchcards

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/ or pastebin (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)

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[–] mykl@lemmy.world 3 points 11 months ago* (last edited 11 months ago)

Dart Solution

Okay, that's more like it. Simple parsing and a bit of recursion, and fits on one screen. Perfect for day 4 :-)

int matchCount(String line) => line
    .split(RegExp('[:|]'))
    .skip(1)
    .map((ee) => ee.trim().split(RegExp(r'\s+')).map(int.parse))
    .map((e) => e.toSet())
    .reduce((s, t) => s.intersection(t))
    .length;

late List matches;
late List totals;

int scoreFor(int ix) {
  if (totals[ix] != 0) return totals[ix];
  return totals[ix] =
      [for (var m in 0.to(matches[ix])) scoreFor(m + ix + 1) + 1].sum;
}

part1(List lines) =>
    lines.map((e) => pow(2, matchCount(e) - 1).toInt()).sum;

part2(List lines) {
  matches = [for (var e in lines) matchCount(e)];
  totals = List.filled(matches.length, 0);
  return matches.length + 0.to(matches.length).map(scoreFor).sum;
}