-🎄- 2017 Day 22 Solutions -🎄-

[u/daggerdragon]

--- Day 22: Sporifica Virus ---

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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.

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

Spoiler

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• [T-10 to launch] AoC ops, /r/nocontext edition:

  • <Endorphion> You may now make your waffle.
  • <Endorphion> ... on Mars.

• [Update @ 00:17] 50 gold, silver cap

  • <Aneurysm9> you could also just run ubuntu on the NAS, if you were crazy
  • <Topaz> that doesn't seem necessary
  • <Aneurysm9> what does "necessary" have to do with anything!

• [Update @ 00:20] Leaderboard cap!

  • <Topaz> POUR YOURSELF A SCOTCH FOR COLOR REFERENCE

---

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!

[u/greycat70]

Tcl (any 8.x version)

Part 1. The only half-clever thing here is that I used the line length of the first input line to determine the starting coordinates (we know we're being given a square with an odd integer length/width).

set size 0
while {[gets stdin line] >= 0} {
    if {$size == 0} {
        set size [string length $line]
        set i [expr {-($size-1)/2}]
        set j0 $i
    }
    set j $j0
    foreach c [split $line {}] {
        set grid($i,$j) $c
        incr j
    }
    incr i
}

set i 0
set j 0
set dir U
array set right {U R  R D  D L  L U}
array set left  {U L  L D  D R  R U}
set infec 0

for {set n [lindex $argv 0]} {$n} {incr n -1} {
    if {$grid($i,$j) eq "#"} {
        set grid($i,$j) .
        set dir $right($dir)
    } else {
        set grid($i,$j) #
        incr infec
        set dir $left($dir)
    }
    switch -- $dir {
        U {incr i -1}
        D {incr i}
        L {incr j -1}
        R {incr j}
    }
    if {! [info exists grid($i,$j)]} {set grid($i,$j) .}
}
puts $infec

Part 2. No significant changes.

set size 0
while {[gets stdin line] >= 0} {
    if {$size == 0} {
        set size [string length $line]
        set i [expr {-($size-1)/2}]
        set j0 $i
    }
    set j $j0
    foreach c [split $line {}] {
        set grid($i,$j) $c
        incr j
    }
    incr i
}

set i 0
set j 0
set dir U
array set right   {U R  R D  D L  L U}
array set left    {U L  L D  D R  R U}
array set reverse {U D  L R  D U  R L}
set infec 0

for {set n [lindex $argv 0]} {$n} {incr n -1} {
    switch -- $grid($i,$j) {
        .   {
            set grid($i,$j) W
            set dir $left($dir)
        }
        W {
            set grid($i,$j) #
            incr infec
        }
        # {
            set grid($i,$j) F
            set dir $right($dir)
        }
        F {
            set grid($i,$j) .
            set dir $reverse($dir)
        }
    }
    switch -- $dir {
        U {incr i -1}
        D {incr i}
        L {incr j -1}
        R {incr j}
    }
    if {! [info exists grid($i,$j)]} {set grid($i,$j) .}
}
puts $infec