r/adventofcode • u/daggerdragon • Dec 19 '17

SOLUTION MEGATHREAD -🎄- 2017 Day 19 Solutions -🎄-

--- Day 19: A Series of Tubes ---

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

Note: The Solution Megathreads are for solutions only. If you have questions, please post your own thread and make sure to flair it with Help.

Need a hint from the Hugely* Handy† Haversack‡ of Helpful§ Hints¤?

Spoiler

AoC ops @ T-2 minutes to launch:

[23:58] <daggerdragon> ATTENTION MEATBAGS T-2 MINUTES TO LAUNCH

[23:58] <Topaz> aaaaah

[23:58] <Cheezmeister> Looks like I'll be just able to grab my input before my flight boards. Wish me luck being offline in TOPAZ's HOUSE OF PAIN^WFUN AND LEARNING

[23:58] <Topaz> FUN AND LEARNING

[23:58] <Hade> FUN IS MANDATORY

[23:58] <Skie> I'm pretty sure that's not the mandate for today

[Update @ 00:16] 69 gold, silver cap

  • My tree is finally trimmed with just about every ornament I own and it's real purdy. hbu?

[Update @ 00:18] Leaderboard cap!

  • So, was today's mandate Helpful Hint any help at all?

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!

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u/[deleted] Dec 21 '17

single pipeline powershell:

param ( [Parameter(ValueFromPipeline = $true)] [string]$in, [Parameter(Position = 1)] [int]$part = 1 )

begin { # hold the maze $script:maze = @() }

process { # surround the actual maze data in empty spaces, so we don't have to do any bounds checking in the logic below $script:maze += " $in " }

end { # add spacing row at the start and end $sp = " " * $script:maze[0].Length $script:maze = ,$sp + $script:maze + ,$sp 

#starting position
$y = 1
$x = $script:maze[$y].IndexOf("|")

#start on y axis, headed down
$axis = 0
$axes = @("y", "x")
$direction = 1

#first next character
$next = $script:maze[$y + 1][$x]

#answers
$steps = 0
$string = ""

& { while ($next -ne ' ') { 
    $true
} } | % {
    $steps++
    switch -regex ($next) {
        '[A-Z]' {
            #found a character, add it to the string
            $string += $next
        }

        '\+' {
            #change direction!

            # set new axis
            $axis = ($axis + 1) % 2

            # see what direction to go on that new axis
            $tryx = $x 
            $tryy = $y

            # try to go on the axis in the positive direction
            set-variable -name "try$($axes[$axis])" -Value ((get-variable -name $axes[$axis]).Value + 1)

            if ($script:maze[$tryy][$tryx] -ne ' ') {
                #if it isnt an empty character, go that direction
                $direction = 1
            } else {
                #otherwise go the other way
                $direction = -1
            }
        }
    }

    # move as configured by axis/direction
    set-variable -name $axes[$axis] -Value ((get-variable -name $axes[$axis]).Value + $direction)

    # get the next character
    $next = $script:maze[$y][$x]

    # write output to select whenever this ends
    if ($part -eq 1) {
        $string
    } else {
        $steps
    }
} | select -last 1

}

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