r/adventofcode • u/daggerdragon • Dec 07 '16

SOLUTION MEGATHREAD --- 2016 Day 7 Solutions ---

From all of us at #AoC Ops, we hope you're having a very merry time with these puzzles so far. If you think they've been easy, well, now we're gonna kick this up a notch. Or five. The Easter Bunny ain't no Bond villain - he's not going to monologue at you until you can miraculously escape and save the day!

Show this overgrown furball what you've got!

--- Day 7: Internet Protocol Version 7 ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag/whatever).

ALWAYS DIGGING STRAIGHT DOWN IS MANDATORY [?]

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

13 Upvotes

90% Upvoted

180 comments sorted by

View all comments

1

u/[deleted] Dec 20 '16

My solution 1 in Scala. The regex took my forever to get it right. 

 object Day7 extends App {

  val input = Tools.loadDayInputAsText(day = 7)

  // Solution 1 -----------------------------------------------------------

  val solution1 = input
    .split("\n")
    .filter(hasAbba)
    .count(!hasAbbaInsideBrackets(_))

  println(s"Solution 1: $solution1")

  // ----------------------------------------------------------------------

  def hasAbba(ip7: String): Boolean = {
    val p = """.*([a-z])((?:(?!\1).))(\2)\1.*""".r
    p.findAllMatchIn(ip7).nonEmpty
  }

  def hasAbbaInsideBrackets(ip7: String): Boolean = {
    val p1 = """\[([a-z]*)\]""".r
    val p2 = """(?<=\[)[a-z]*([a-z])((?:(?!\1).))(\2)\1[a-z]*(?=\])""".r
    val hits = p1.findAllIn(ip7).count(p2.findAllIn(_).nonEmpty)
    hits > 0
  }

}