Rules: no spoilers.

The other rules are made up as we go along.

Share code by link to a forge, home page, pastebin (Eric Wastl has one here) or code section in a comment.

top 50 comments

sorted by: hot top controversial new old
[–] 7 points 2 years ago* (last edited 2 years ago) (2 children)

day 1

part 1

perl

#!/usr/bin/env perl

use strict;
use warnings;
use 5.010;

my $total = 0;

for my $line (<>) {
    my @nums = ($line =~ /\d/g);
    $total += $nums[0] * 10 + $nums[-1];
}

say $total;

part 2

perl

#!/usr/bin/env perl

use strict;
use warnings;
use v5.010;

my %nums = (one => 1, two => 2, three => 3, four => 4, five => 5, six => 6, seven => 7, eight => 8, nine => 9);
$nums{$_} = $_ for 1..9;

my $regex = join "|", keys %nums;

my $total = 0;

for my $line (<>) {
    $line =~ /($regex)/;
    my $first_num = $nums{$1};

    my $window = 1;
    my $sub = substr $line, -1;
    while ($sub !~ /($regex)/) {
        $window ++;
        $sub = substr $line, -$window;
    }

    $sub =~ /($regex)/;
    my $second_num = $nums{$1};

    $total += $first_num * 10 + $second_num;
}

say $total;

Part 2 gave me a surprising amount of trouble. I resolved it by looking at longer and longer substrings from the end of the line in order to find the very last word even if it overlapped, which you can't do with normal regex split. I doubt this is the most efficient possible solution.

Also Lemmy is eating my < characters inside code blocks, which seems wrong. Pretend the "&lt;>" part says "<>", lol

  • source
  • hideshow 2 child comments
  • [–] 4 points 2 years ago

    day 2

    perl

    #!/usr/bin/env perl
    
    use strict;
    use warnings;
    use v5.010;
    use List::Util qw/ max /;
    
    # Parse the input
    
    my %games = ();
    
    for my $line (&lt;>) {
        $line =~ /Game (\d+): (.+)/;
        my $game_id = $1;
        my $game_str = $2;
    
        my @segments = split '; ', $game_str;
        my @game = ();
        for my $segment (@segments) {
            my @counts = split ', ', $segment;
    
            my %colors = (red => 0, blue => 0, green => 0);
            for my $count (@counts) {
                $count =~ /(\d+) (\w+)/;
                $colors{$2} = $1;
            }
    
            push @game, { %colors };
        }
    
        $games{$game_id} = [ @game ];
    }
    
    # Part 1
    
    my $part1 = 0;
    
    game: for my $game_id (keys %games) {
        for my $segment (@{$games{$game_id}}) {
            next game if $segment->{red} > 12 || $segment->{green} > 13 || $segment->{blue} > 14;
        }
    
        $part1 += $game_id;
    }
    
    say "Part 1: $part1";
    
    # Part 2
    
    my $part2 = 0;
    
    for my $game (values %games) {
        my ($red, $green, $blue) = (0, 0, 0);
    
        for my $segment (@$game) {
            $red = max $segment->{red}, $red;
            $green = max $segment->{green}, $green;
            $blue = max $segment->{blue}, $blue;
        }
    
        $part2 += $red * $green * $blue;
    }
    
    say "Part 2: $part2";
    

    Found this much easier than day 1 honestly...

  • source
  • parent
  • [–] 7 points 2 years ago* (last edited 2 years ago) (3 children)

    Just when I think I'm out, awful systems pulls me right back in.

    C++, Horrifying C++ for day 1b check it out ;)

    Day 1: https://www.animeprincess.net/blog/?p=55

    One day is enough for me though, writing deliberately off-the-wall code is surprisingly mentally taxing, and normally I make sure to never program outside of work.

  • source
  • hideshow 3 child comments
  • [–] 4 points 2 years ago (2 children)

    // Where we're going we won't need regexes.

    fuck yes

  • source
  • parent
  • hideshow 2 child comments
  • [–] 4 points 2 years ago (1 child)

    honestly I considered writing a parser-based approach

    then I was too tired and thought "hmm, doing this with grok would be funny", but I didn't have logstash handy and fuck dealing with containers at midnight

    I will, however, do that today

  • source
  • parent
  • hideshow 1 child comment
  • [–] 4 points 2 years ago

    Status report: grok allows for non-greedy matching but still captures greedily for term assignment. I think I have a workaround that might work (recursively pipe data back to itself, gated on length for action), need to test later

    This particular flavour of parsecrime is near guaranteed to be of interest to very few, but I want to see if I can make it work nonetheless. That’s just how my brainworms work.

  • source
  • parent
  • [+] 5 points 2 years ago
    [+] 5 points 2 years ago* (last edited 2 years ago)
    [+] 5 points 2 years ago* (last edited 2 years ago)
    [–] 4 points 2 years ago (2 children)

    Back to a more straightfoward day, do they make them harder on the weekends?

    Day 4 Scratchcards

    Part 1

    #!/usr/bin/env jq -n -R -f
    [
      inputs
      # Split winning numbers | card
      | split(" | ")
      # Get numbers, remove game id
      | .[] |= [ match("\\d+"; "g").string | tonumber ] | .[0] |= .[1:]
      # Get score for each line
      | .[1] - (.[1] - .[0]) | length | select(. > 0) | pow(2; . - 1)
    ]
    
    # Output total score sum
    | add
    

    Very suited to JQ, extra trick learned using: [ match("\\d+"; "g").string | tonumber ] as a parse all ints in line.

    Part 2

    #!/usr/bin/env jq -n -R -f
    [
      inputs
      # Split winning numbers | card
      | split(" | ")
      # Get numbers, remove game id
      | .[] |= [ match("\\d+"; "g").string | tonumber ] | .[0] |= .[1:]
      # Set number of cards to 1, and further cards count
      | .[1] - (.[1] - .[0]) | [ 1, length ]
    ]
    
    | { cards: ., i: 0, l: length } | until (.i == .l;
      # Get number for current card
      .cards[.i][0] as $num
      # Increase range of futher cards, by current number
      | .cards[.i + range(.cards[.i][1]) + 1 ][0] += $num
      | .i += 1
    )
    
    # Output total sum of cards
    | [ .cards[][0] ] | add
    

    Not too much of an edit compared to part one, being able to easily do operations on range of indices is convenient.

  • source
  • hideshow 2 child comments
  • [–] [S] 4 points 2 years ago

    Historically problems on Sat/Sun have been more challenging than weekdays. However given that the first 7 days are usually “warmup” problems, I’d say this years edition of AoC is more challenging than at least since 2019.

  • source
  • parent
  • [–] 4 points 2 years ago* (last edited 1 year ago) (12 children)

    I am using dart to develop my dart chops. DM me for code.

  • source
  • hideshow 12 child comments
  • [–] 4 points 2 years ago

    1 a,b:as a professional software engineer, I know that googling regex syntax and getting it right will take longer than manually writing string comparisons, so... here's all you need to see of my final solution.

      int? check3(String line, int index) {
        if (line.length &lt; index + 3) {
          return null;
        }
    
        String sub = line.substring(index, index + 3);
        return sub == "one"
            ? 1
            : sub == "two"
                ? 2
                : sub == "six"
                    ? 6
                    : null;
      }
    

  • source
  • parent
  • [–] 4 points 2 years ago (1 child)

    Nice, I’ll be reading :D

    (Possibly have some dart coming up on a thing soon)

  • source
  • parent
  • hideshow 1 child comment
  • [–] 4 points 2 years ago

    I'll be honest: so far, Dart is pretty rubbish for this kind of exercise for the simple reason that their Strings aren't just arrays of chars. There's no native isDigit, for example. Otherwise, I've been using it with Flutter and have been happy with my experience.

    I'm only posting code when I think I've done something interesting or if there's a notable language feature to show off, but so far, no dice.

  • source
  • parent
  • [–] 3 points 2 years ago

    4 aNot so bad today. I bit the bullet and tried to see if dart has tuples or similar. It does, by the name of "records". Now instead of pretending I'm writing in C/C++, I can pretend I'm writing in python.

    Anyway, a) is a pretty straightforward job-interview style question, except AoC doesn't care about efficiency. Still, we all have our own versions of pride, so I did it with a set (Though whether or not dart's native Set is tree or hash based is not known to me right now).

    code

    int matches(String line) {
      ({List wn, List n}) card = getNumbers(line);
      Set wn = Set.from(card.wn);
    
      return card.n.fold(0, (prev, e) => prev + (wn.contains(e) ? 1 : 0));
    }
    
    void day4a(List lines) {
      print(lines.fold(0, (acc, line) {
        int m = matches(line);
        return acc + (m != 0 ? (1 &lt;&lt; (m - 1)) : 0);
      }));
    }
    

    4bb) was a little harder, and definitely a possible trap for overthinking. I think the easiest way to think about solving this is as if it is a dynamic programming problem (though it kinda isn't).

    So the general approach is to formulate it like this:

    T_n(total cards won by card n) = M_n(total matches for card n) + CW_n(total cards won by the copies that card n wins).

    and

    CW_n =

    • 0 if M_n = 0
    • sum of T_i, where i = n + 1 ... n + M_n

    Caching T_n is the DP trick to making this performant (though once again, it does not need to be)

    Anyway, the above approach is the top-down version of the DP; the bottom-up version is what I actually started with in my head. I gave up on that approach because I felt like the logic was too hard for me to figure out.

    code:

    void day4b(List lines) {
      List totalMatches = lines.map((e) => matches(e)).toList();
    
      // total copies won, including copies won from copies.
      List cachedWins = List.filled(totalMatches.length, -1);
      int totalWins(int i) {
        // return cached result if it exists
        if (cachedWins[i] > 0) {
          return cachedWins[i];
        }
    
        int count = totalMatches[i];
        // count the copies won from the subsequent copied cards
        for (int j = 1; j &lt;= totalMatches[i]; j++) {
          count += totalWins(i + j);
        }
    
        // cache the result
        cachedWins[i] = count;
        return count;
      }
    
      int totalCards = totalMatches.length; // count all the originals
      // count all the wins
      for (int i = 0; i &lt; totalMatches.length; i++) {
        totalCards += totalWins(i);
      }
      print(totalCards);
    }
    

  • source
  • parent
  • load more comments (8 replies)
    [–] [S] 4 points 2 years ago (1 child)

    Day 11: Cosmic Expansion

    https://adventofcode.com/2023/day/11

    discussion

    After yesterday' fiddle-fest we are back with a straight-forward puzzle. Today we get the return of Manhattan distance, an AoC fav, but this time not spelled out to fool the crafty LLMs.

    I made the initial decision not to "move" the galaxies in the initial map, but instead to store an offset that was increased whenever an empty row or column preceding the object was detected. This turned out to make part 2 really easy once I figured out the off-by-one error.

  • source
  • hideshow 1 child comment
  • load more comments (1 reply)
    [–] [S] 4 points 2 years ago (1 child)

    Day 14: Parabolic Reflector Dish

    I only managed part 1 today. My enthusiasm for index fiddling is waning rapidly.

  • source
  • hideshow 1 child comment
  • [–] 4 points 2 years ago

    How about not fiddling with indices?

    JQ Notfiddlingwithindexificationhttps://github.com/zogwarg/advent-of-code/blob/main/2023/jq/14-a.jq

    #!/usr/bin/env jq -n -R -f
    
    # Dish to grid
    [ inputs / "" ]
    
    # Tilt UP
    | transpose                       # Transpose, for easier RE use
    | map(                            #
      ("#" + add) | [                 # For each column,   replace '^' with '#'
        scan("#[O.]*") | [            # From '#' get empty spaces and 'O' rocks
          "#", scan("O"), scan("\\.") # Let gravity do it's work.
        ]                             #
      ] | add[1:]                     # Add groups back together
     )                                #
    | transpose                       # Transpose back
    
    # For each row, count  'O'  rocks
    | map(add | [scan("O")] | length)
    
    # Add total load on "N" beam
    | [0] + reverse | to_entries
    | map( .key * .value ) | add
    

    Similarly tired with index fiddling, I was pretty happy with my approach, which led to satisfying transpose cancelling in part 2. Not the fastest code out there, but it works. Day 14 was actually my favorite one so far ^^.

  • source
  • parent
  • [–] [S] 4 points 2 years ago (1 child)

    Day 2: Cube Conundrum

    https://adventofcode.com/2023/day/2

    Parsing the puzzle (both instructions and input) was the hardest this time for me.

  • source
  • hideshow 1 child comment
  • [–] [S] 4 points 2 years ago (11 children)
  • [–] [S] 4 points 2 years ago (10 children)

    Perl: https://github.com/gustafe/aoc2023/blob/main/d01-Trebuchet.pl

    thoughts

    I found this really tough for a day 1 problem. Because I don't really know regex, I did not know the secret to finding overlapping patterns. I quickly figured out that "twone" was a possibility, because it was in the example, but then I had to find other examples and hardcode them into my split pattern.

    This isn't general, my input doesn't have 'sevenine' for example.

  • source
  • parent
  • hideshow 10 child comments
  • load more comments (1 reply)
  • [–] 4 points 2 years ago

    Day 4: Scratchcards

    Late to the party and never done advents before, I liked how this problem reminded me that tree traversal is thing, almost as much as I don't that so much of my career involves powershell now.

    I'm putting everything up at https://github.com/SpaceAntelope/advent-of-code-2023 except the input files.

    Using command abbreviations like % and ? to keep the horizontal length friendly to lemmy post areas, they are expanded in git.

    Part 2 in Powershell

    function calculate([string]$data) {
      # code for parsing data and calculating matches from pt1 here, check the github link if you like banal regexps
      # returns objects with the relevant fields being the card index and the match count
    }
    
    function calculateAccumulatedCards($data) {
        $cards = calculate $data # do pt1 calculations
    
        $cards 
        | ? MatchCount -gt 0 # otherwise the losing card becomes its own child and the search cycles to overflow
        | % { 
            $children = ($_.Index + 1) .. ($_.Index + $_.MatchCount)  # range of numbers corresponding to indices of cards won
            | % { $cards[$_ - 1] } # map to the actual cards
            | ? { $null -ne $_ }  # filter out overflow when index exceeds input length
    
            $_ | Add-Member -NotePropertyName Children -NotePropertyValue $children # add cards gained as children property
        }
    
        # do depth first search on every card and its branching children while counting every node
        # the recursive function is inlined in the foreach block because it's simpler than referencing it 
        # from outside the parallel scope
        $cards | % -Parallel {
            function traverse($card) {
                $script:count++        
                foreach ($c in $card.Children) { traverse($c) }
            }
            
            $script:count = 0 # script: means it's basically globally scoped
            traverse $_ 
            $script:count # pass node count to pipeline     
        } 
        | measure -sum    
        | % sum
    }
    

  • source
  • [–] 4 points 2 years ago

    Have been mostly using jq for fun.

    Day 1

    Part 1

    #!/usr/bin/env jq -n -R -f
    
    # Get and reduce every "pretty" line
    reduce inputs as $line (
      0;
      # Add extracted number
      . + ( $line / "" | [ .[] | tonumber? ] | [first * 10 , last] | add )
    )
    

    First part was easy, and very suited to jq

    Part 2

    #!/usr/bin/env jq -n -R -f
    
    # Define string to num value map
    {
      "one":   1,  "1": 1,
      "two":   2,  "2": 2,
      "three": 3,  "3": 3,
      "four":  4,  "4": 4,
      "five":  5,  "5": 5,
      "six":   6,  "6": 6,
      "seven": 7,  "7": 7,
      "eight": 8,  "8": 8,
      "nine":  9,  "9": 9
    } as $to_num |
    
    # Get and reduce every "pretty" line
    reduce inputs as $line (
      0;
      . + (
        $line |
        # Try two capture two numbers
        capture("(^.*?(?(one|two|three|four|five|six|seven|eight|nine|[1-9])).*(?(one|two|three|four|five|six|seven|eight|nine|[1-9])).*?$)?") |
        # If no capture, get one number twice
        if .f == "" then $line | capture("^.*?(?(one|two|three|four|five|six|seven|eight|nine|[1-9]))") | .l = .f else . end |
        # Add extracted number
        $to_num[.f] * 10 + $to_num[.l]
      )
    )
    

    Second part was harder than expected, i had to resort to regex.

    Day 2

    Part 1

    #!/usr/bin/env jq -n -R -f
    
    # For each game: Is 12 red cubes, 13 green cubes, and 14 blue cubes possible ?
    # Line Format =
    # Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
    [
      # Splitting input game id and content
      inputs / ": " |
      # Saving id
      (.[0] / " " | .[1] | tonumber ) as $id |
      # Parsing game
      .[1] / "; " | [
        .[] / ", " | [ .[] / " " | {(.[1]): .[0] | tonumber} ] | add |
        # Is given sample possible ?
        .red &lt;= 12 and .green &lt;= 13 and .blue &lt;= 14
      ] |
      # If all samples possible, return id, else 0
      if all then $id else 0 end
    ] |
    
    # Return sum of all possible game ids
    add
    

    Not too much trickery in this example.

    Part 2

    #!/usr/bin/env jq -n -R -f
    
    # Line Format =
    # Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
    [
      # Splitting input game id and content
      inputs / ": " |
      # Parsing game
      .[1] / "; " |
        [ .[] / ", " | [ .[] / " " | {(.[1]): .[0] | tonumber} ] | add ] |
        # Getting minimum required mumber for each color,
        # and computing the power
        {
          r: ([.[].red]   | max),
          g: ([.[].green] | max),
          b: ([.[].blue]  | max)
        } | .r * .g * .b
    ] |
    
    # Return sum of all powers
    add
    

    Satisifyingly straightfoward edit form part one.

    Day 3

    Part 1

    #!/usr/bin/env jq -n -R -f
    
    # Getting input with padding, and padded width
    [ "." + inputs + "." ] as $inputs | ( $inputs[0] | length ) as $w |
    
    # Working with flattened string, convert all symbols to '#'
    [
      ([range($w) | "."]|join("")), # Padding
      $inputs[],
      ([range($w) | "."]|join(""))  # Padding
    ] | join("") | gsub("[^0-9.]";"#") as $inputs |
    
    reduce (
      # Get all indices for symbols, in box pattern around symbols
      $inputs | indices("#")[] |
      . - $w -1  , . - $w , . - $w + 1 ,
      . - 1      , empty  , . + 1      ,
      . + $w - 1 , . + $w , . + $w + 1
    ) as $i (
      # Numbers containes bounding indices,
      # of numbers bordering symbols
      {numbers: []};
    
      # Test if current index isn't included in any found number
      def new_number($i): [ .numbers[] | .[0] &lt;= $i and $i &lt;= .[1] ] | any | not ;
      # Make "number" as bounding indices, by extending left and right
      def make_number($i):
        {a: $i, b: ($i+1 )}
          | until( $inputs[.a:.b] | test("^[^0-9]"); .a -= 1 )
          | until( $inputs[.a:.b] | test("[^0-9]$"); .b += 1 )
          | [ .a +1 , .b -1 ]
      ;
    
      # Add numbers if bordering symbol and new
      if ($inputs[$i:$i+1] | test("[0-9]")) and new_number($i) then .numbers += [ make_number($i) ] else . end
    ) |
    
    # Output sum of all found numbers
    [ .numbers[] | $inputs[.[0]:.[1]] | tonumber ] | add
    

    Took More time than i expected, glad i had the idea early to search by the indices of the symbols and not the digits. Not super well suited to jq, unless I'm missing a better solution.

    Part 2

    #!/usr/bin/env jq -n -R -f
    
    # Getting input with padding, and padded width
    [ "." + inputs + "." ] as $inputs | ( $inputs[0] | length ) as $w |
    
    # Working with flattened string, only keep gear '*' symbols
    [
      ([range($w) | "."]|join("")), # Padding
      $inputs[],
      ([range($w) | "."]|join(""))  # Padding
    ] | join("") | gsub("[^0-9*]";".") as $inputs |
    
    # Iterate over index positions of all gears
    reduce ($inputs | indices("*")[]) as $i (
      0;
      # Re-use part-1 functions
      def new_number($i):
        [ .numbers[] | .[0] &lt;= $i and $i &lt;= .[1] ] | any | not
      ;
      def make_number($i):
        {a: $i, b: ($i+1 )}
          | until( $inputs[.a:.b] | test("^[^0-9]"); .a -= 1 )
          | until( $inputs[.a:.b] | test("[^0-9]$"); .b += 1 )
          | [ .a +1 , .b -1 ]
      ;
      # Reset and add numbers for each "box" ids
      def add_numbers($box_idx):
        reduce $box_idx[] as $i ({numbers:[]};
          if ($inputs[$i:$i+1] | test("[0-9]")) and new_number($i) then
            .numbers += [ make_number($i) ]
          else
            .
          end
        )
      ;
      add_numbers([
        $i - $w -1 , $i - $w , $i -$w + 1 ,
        $i - 1     , empty   , $i + 1     ,
        $i + $w - 1, $i + $w , $i + $w + 1
      ]).numbers as $numbers |
    
      if $numbers | length == 2 then
        # Add product if exactly two bordering numbers
        . += ( $numbers | map($inputs[.[0]:.[1]]|tonumber) | .[0] * .[1] )
      else
        .
      end
    )
    

    Not too far of an edit from part one.

  • source
  • [–] [S] 3 points 2 years ago
    load more comments
    view more: next ›