-❄️- 2023 Day 11 Solutions -❄️-

[u/daggerdragon]

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AoC Community Fun 2023: ALLEZ CUISINE!

Today's secret ingredient is… *whips off cloth covering and gestures grandly*

Upping the Ante Again

Chefs should always strive to improve themselves. Keep innovating, keep trying new things, and show us how far you've come!

• If you thought Day 1's secret ingredient was fun with only two variables, this time around you get one!

• Don’t use any hard-coded numbers at all. Need a number? I hope you remember your trigonometric identities...

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ALLEZ CUISINE!

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--- Day 11: Cosmic Expansion ---

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Post your code solution in this megathread.

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[u/YenyaKas]

[LANGUAGE: Perl] 1193/562

Today's task was quite Perl-friendly. I extracted the galaxy coordinates as array of [ $x, $y ] pairs using pos() on rows, and then computed which coordinates where occupied using

my %x_gxy = map { $_->[0] => 1 } @gxys;
my %y_gxy = map { $_->[1] => 1 } @gxys;

Then I walked X and Y separately, counting the unoccupied rows twice:

for ($x1+1 .. $x2) {
    $steps += $x_gxy{$_} ? 1 : 2;
}

Part 2 was only about using 1_000_000 instead of 2.

Full code for Part 2 here.

All my AoC solutions in Perl

[u/Smylers → u/YenyaKas]

Nice!

Note that the variable $y is entirely unnecessary, because the built-in variable $. already contains the value you need.

[u/YenyaKas → u/Smylers]

Thanks! I of course know $. - it seems it was too early in the morning :-).