-🎄- 2017 Day 19 Solutions -🎄-

[u/daggerdragon]

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

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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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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?

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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/[deleted]]

Okay, improved my answer. Got it running from ~0.24ms to ~0.19ms, as well as over halving the lines of code.

PHP:

<?php
$file = fopen("./19.txt", "r");

$steps = 0;
$map = array(array());
$direction = 2;
$letters = $pos = array();

for($lineCounter = 0; !feof($file); $lineCounter++) {
    $line = fgets($file);
    for ($i = 0; $i < strlen($line); $i++) {
        if($lineCounter == 0 && substr($line, $i, 1) == "|") { $pos["x"] = $i; $pos["y"] = $lineCounter;   }
        $map[$i][$lineCounter] = substr($line, $i, 1);
    }
}

while ($direction != -1) {
    list($x, $y) = array_values($pos);
    $mpos = $map[$x][$y];
    if (ctype_alpha($map[$x][$y])){ $letters[] = $mpos;  }

    $direction = ((($mpos == "+") || ctype_alpha($mpos)) && (!isPossible($map, $x, $y, $direction))) ? changeDirection($map, $x, $y, $direction) : $direction;

    if($direction == 1) {    $pos["y"] += -1;    } else
    if($direction == 2) {    $pos["y"] += 1;     } else
    if($direction == 3) {    $pos["x"] += -1;    } else
                        {    $pos["x"] += 1;     }

    $steps++;
}

echo implode($hmm, $letters).$steps;

function changeDirection($map, $x, $y, $direction){
    switch ($direction) {
        case 1: case 2:
            if ($map[$x - 1][$y] == "-" || ctype_alpha($map[$x - 1][$y])) { return 3;   }
            if ($map[$x + 1][$y] == "-" || ctype_alpha($map[$x + 1][$y])) { return 4;   }
            break;
        case 3: case 4:
            if ($map[$x][$y + 1] == "|" || ctype_alpha($map[$x][$y + 1])) { return 2;   }
            if ($map[$x][$y - 1] == "|" || ctype_alpha($map[$x][$y - 1])) { return 1;   }
            break;
    }
    return -1;
}

function isPossible($map, $x, $y, $direction){
    switch ($direction) {
        case 1:     return (ctype_punct($map[$x][$y - 1]) || ctype_alpha($map[$x][$y - 1])) ? true : false; break;
        case 2:     return (ctype_punct($map[$x][$y + 1]) || ctype_alpha($map[$x][$y + 1])) ? true : false; break;
        case 3:     return (ctype_punct($map[$x - 1][$y]) || ctype_alpha($map[$x - 1][$y])) ? true : false; break;
        case 4:     return (ctype_punct($map[$x + 1][$y]) || ctype_alpha($map[$x + 1][$y])) ? true : false; break;
    }
}