this post was submitted on 23 Dec 2024
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current difficulties

  1. Day 21 - Keypad Conundrum: 01h01m23s
  2. Day 17 - Chronospatial Computer: 44m39s
  3. Day 15 - Warehouse Woes: 30m00s
  4. Day 12 - Garden Groups: 17m42s
  5. Day 20 - Race Condition: 15m58s
  6. Day 14 - Restroom Redoubt: 15m48s
  7. Day 09 - Disk Fragmenter: 14m05s
  8. Day 16 - Reindeer Maze: 13m47s
  9. Day 22 - Monkey Market: 12m15s
  10. Day 13 - Claw Contraption: 11m04s
  11. Day 06 - Guard Gallivant: 08m53s
  12. Day 08 - Resonant Collinearity: 07m12s
  13. Day 11 - Plutonian Pebbles: 06m24s
  14. Day 18 - RAM Run: 05m55s
  15. Day 04 - Ceres Search: 05m41s
  16. Day 23 - LAN Party: 05m07s
  17. Day 02 - Red Nosed Reports: 04m42s
  18. Day 10 - Hoof It: 04m14s
  19. Day 07 - Bridge Repair: 03m47s
  20. Day 05 - Print Queue: 03m43s
  21. Day 03 - Mull It Over: 03m22s
  22. Day 19 - Linen Layout: 03m16s
  23. Day 01 - Historian Hysteria: 02m31s
top 12 comments
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[–] [email protected] 2 points 14 hours ago

It's a wrap!

One of the easier years imho. Better than last year in any case.

I get the feeling that this is Eric's way of saying goodbye, and that this might be the last year, but I might be wrong.

Puzzles by difficulty (leaderboard completion times)

  1. Day 21 - Keypad Conundrum: 01h01m23s
  2. Day 24 - Crossed Wires: 01h01m13s
  3. Day 17 - Chronospatial Computer: 44m39s
  4. Day 15 - Warehouse Woes: 30m00s
  5. Day 12 - Garden Groups: 17m42s
  6. Day 20 - Race Condition: 15m58s
  7. Day 14 - Restroom Redoubt: 15m48s
  8. Day 09 - Disk Fragmenter: 14m05s
  9. Day 16 - Reindeer Maze: 13m47s
  10. Day 22 - Monkey Market: 12m15s
  11. Day 13 - Claw Contraption: 11m04s
  12. Day 06 - Guard Gallivant: 08m53s
  13. Day 08 - Resonant Collinearity: 07m12s
  14. Day 11 - Plutonian Pebbles: 06m24s
  15. Day 18 - RAM Run: 05m55s
  16. Day 04 - Ceres Search: 05m41s
  17. Day 23 - LAN Party: 05m07s
  18. Day 25 - Code Chronicle: 04m43s
  19. Day 02 - Red Nosed Reports: 04m42s
  20. Day 10 - Hoof It: 04m14s
  21. Day 07 - Bridge Repair: 03m47s
  22. Day 05 - Print Queue: 03m43s
  23. Day 03 - Mull It Over: 03m22s
  24. Day 19 - Linen Layout: 03m16s
  25. Day 01 - Historian Hysteria: 02m31s
[–] [email protected] 2 points 21 hours ago (2 children)

25!

p1 tipsO(mn)/O(n^2^) is fast enough.

50 stars baby!https://imgur.com/a/hwEVy9H

[–] [email protected] 3 points 15 hours ago

congrats! I still have 6 stars to go, but I still think this was easier than last year.

[–] [email protected] 2 points 20 hours ago

And done! well I had fun.

[–] [email protected] 3 points 1 day ago* (last edited 1 day ago) (1 children)

24! - Crossed Wires - Leaderboard time 01h01m13s (and a close personal time of 01h09m51s)

SpoilersI liked this one! It was faster the solve part 2 semi-manually before doing it "programmaticly", which feels fun.

Way too many lines follow (but gives the option to finding swaps "manually"):

#!/usr/bin/env jq -n -crR -f

( # If solving manually input need --arg swaps
  # Expected format --arg swaps 'n01-n02,n03-n04'
  # Trigger start with --arg swaps '0-0'
  if $ARGS.named.swaps then $ARGS.named.swaps |
    split(",") | map(split("-") | {(.[0]):.[1]}, {(.[1]):.[0]}) | add
  else {} end
) as $swaps |

[ inputs | select(test("->")) / " " | del(.[3]) ] as $gates |

[ # Defining Target Adder Circuit #
  def pad: "0\(.)"[-2:];
  (
    [ "x00", "AND", "y00", "c00" ],
    [ "x00", "XOR", "y00", "z00" ],
    (
      (range(1;45)|pad) as $i |
      [ "x\($i)", "AND", "y\($i)", "c\($i)" ],
      [ "x\($i)", "XOR", "y\($i)", "a\($i)" ]
    )
  ),
  (
    ["a01", "AND", "c00", "e01"],
    ["a01", "XOR", "c00", "z01"],
    (
      (range(2;45) | [. , . -1 | pad]) as [$i,$j] |
      ["a\($i)", "AND", "s\($j)", "e\($i)"],
      ["a\($i)", "XOR", "s\($j)", "z\($i)"]
    )
  ),
  (
    (
      (range(1;44)|pad) as $i |
      ["c\($i)", "OR", "e\($i)", "s\($i)"]
    ),
    ["c44", "OR", "e44", "z45"]
  )
] as $target_circuit |

( #        Re-order xi XOR yi wires so that xi comes first        #
  $gates | map(if .[0][0:1] == "y" then  [.[2],.[1],.[0],.[3]] end)
) as $gates |

#  Find swaps, mode=0 is automatic, mode>0 is manual  #
def find_swaps($gates; $swaps; $mode): $gates as $old |
  #                   Swap output wires                #
  ( $gates | map(.[3] |= ($swaps[.] // .)) ) as $gates |

  # First level: 'x0i AND y0i -> c0i' and 'x0i XOR y0i -> a0i' #
  #      Get candidate wire dict F, with reverse dict R        #
  ( [ $gates[]
      | select(.[0][0:1] == "x" )
      | select(.[0:2] != ["x00", "XOR"] )
      | if .[1] == "AND" then { "\(.[3])": "c\(.[0][1:])"  }
      elif .[1] == "XOR" then { "\(.[3])": "a\(.[0][1:])"  }
      else "Unexpected firt level op" | halt_error end
    ] | add
  ) as $F | ($F | with_entries({key:.value,value:.key})) as $R |

  #       Replace input and output wires with candidates      #
  ( [ $gates[]  | map($F[.] // .)
      | if .[2] | test("c\\d") then [ .[2],.[1],.[0],.[3] ] end
      | if .[2] | test("a\\d") then [ .[2],.[1],.[0],.[3] ] end
    ] # Makes sure that when possible a0i comes 1st, then c0i #
  ) as $gates |

  # Second level:   use info rich 'c0i OR e0i -> s0i' gates   #
  #      Get candidate wire dict S, with reverse dict T       #
  ( [ $gates[]
      | select((.[0] | test("c\\d")) and .[1] == "OR" )
      | {"\(.[2])": "e\(.[0][1:])"}, {"\(.[3])": "s\(.[0][1:])"}
    ] | add | with_entries(select(.key[0:1] != "z"))
  ) as $S | ($S | with_entries({key:.value,value:.key})) as $T |

  ( #      Replace input and output wires with candidates     #
    [ $gates[] | map($S[.] // .) ] | sort_by(.[0][0:1]!="x",.)
  ) as $gates  | #                   Ensure "canonical" order #

  [ # Diff - our input gates only
    $gates - $target_circuit
    | .[] | [ . , map($R[.] // $T[.] // .) ]
  ] as $g |
  [ # Diff +  target circuit only
    $target_circuit - $gates
    | .[] | [ . , map($R[.] // $T[.] // .) ]
  ] as $c |

  if $mode > 0 then
    #    Manual mode print current difference    #
    debug("gates", $g[], "target_circuit", $c[]) |

    if $gates == $target_circuit then
      $swaps | keys | join(",") #   Output successful swaps  #
    else
      "Difference remaining with target circuit!" | halt_error
    end
  else
    # Automatic mode, recursion end #
    if $gates == $target_circuit then
      $swaps | keys | join(",") #   Output successful swaps  #
    else
      [
        first(
          # First case when only output wire is different
          first(
            [$g,$c|map(last)]
            | combinations
            | select(first[0:3] == last[0:3])
            | map(last)
            | select(all(.[]; test("e\\d")|not))
            | select(.[0] != .[1])
            | { (.[0]): .[1], (.[1]): .[0] }
          ),
          # "Only" case where candidate a0i and c0i are in an
          # incorrect input location.
          # Might be more than one for other inputs.
          first(
            [
              $g[] | select(
                ((.[0][0]  | test("a\\d")) and .[0][1] == "OR") or
                ((.[0][0]  | test("c\\d")) and .[0][1] == "XOR")
              ) | map(first)
            ]
            | if length != 2 then
                "More a0i-c0i swaps required" | halt_error
              end
            | map(last)
            | select(.[0] != .[1])
            | { (.[0]): .[1], (.[1]): .[0] }
          )
        )
      ] as [$pair] |
      if $pair | not then
        "Unexpected pair match failure!" | halt_error
      else
        find_swaps($old; $pair+$swaps; 0)
      end
    end
  end
;

find_swaps($gates;$swaps;$swaps|length)

[–] [email protected] 2 points 1 day ago* (last edited 1 day ago)

I did part 2 manually! I will not bother writing a code solution unless I feel like it.

well well wellAoC, so you thought you could dredge up my trauma as an EE grad by making me debug a full-adder logic circuit? How dare you. You succeeded.

[–] [email protected] 2 points 1 day ago

22

uhpretty straightforward. At least it's not a grid!

[–] [email protected] 2 points 1 day ago* (last edited 1 day ago)

21!

Finally managed to beat this one into submission.

P1I created this disgusting mess of a recursive search that happened to work. This problem was really hard to think about due to the levels of indirection. It was also hard because of a bug I introduced into my code that would have been easy to debug with more print statements, but hubris.

P2Recursive solution from P1 was too slow, once I was at 7 robots it was taking minutes to run the code. It didn't take long to realise that you don't really care about where the robots other than the keypad robot and the one controlling the keypad robot are since the boundary of each state needs all the previous robots to be on the A button. So with memoisation, you can calculate all the shortest paths for a given robot to each of the directional inputs in constant time, so O(kn) all up where n is the number of robots (25) and k is the complexity of searching for a path over 5 or 11 nodes.

What helped was looking at the penultimate robot's button choices when moving the keypad robot. After the first one or two levels, the transitions settle into the table in the appendix. I will not explain the code.

appendix

  (P(0, 1), P(0, 1)): [],
  (P(0, 1), P(0, 2)): [btn.r],
  (P(0, 1), P(1, 0)): [btn.d, btn.l],
  (P(0, 1), P(1, 1)): [btn.d],
  (P(0, 1), P(1, 2)): [btn.d, btn.r],
  (P(0, 2), P(0, 1)): [btn.l],
  (P(0, 2), P(0, 2)): [],
  (P(0, 2), P(1, 0)): [btn.d, btn.l, btn.l],
  (P(0, 2), P(1, 1)): [btn.l, btn.d],
  (P(0, 2), P(1, 2)): [btn.d],
  (P(1, 0), P(0, 1)): [btn.r, btn.u],
  (P(1, 0), P(0, 2)): [btn.r, btn.r, btn.u],
  (P(1, 0), P(1, 0)): [],
  (P(1, 0), P(1, 1)): [btn.r],
  (P(1, 0), P(1, 2)): [btn.r, btn.r],
  (P(1, 1), P(0, 1)): [btn.u],
  (P(1, 1), P(0, 2)): [btn.u, btn.r],
  (P(1, 1), P(1, 0)): [btn.l],
  (P(1, 1), P(1, 1)): [],
  (P(1, 1), P(1, 2)): [btn.r],
  (P(1, 2), P(0, 1)): [btn.l, btn.u],
  (P(1, 2), P(0, 2)): [btn.u],
  (P(1, 2), P(1, 0)): [btn.l, btn.l],
  (P(1, 2), P(1, 1)): [btn.l],
  (P(1, 2), P(1, 2)): [],

[–] [email protected] 2 points 2 days ago (3 children)

23!

SpoilerificGot lucky on the max clique in part 2, my solution only works if there are at least 2 nodes in the clique, that only have the clique members as common neighbours.

Ended up reading wikipedia to lift one the Bron-Kerbosch methods:

#!/usr/bin/env jq -n -rR -f

reduce (
  inputs / "-" #         Build connections dictionary         #
) as [$a,$b] ({}; .[$a] += [$b] | .[$b] += [$a]) | . as $conn |


#  Allow Loose max clique check #
if $ARGS.named.loose == true then

# Only works if there is at least one pair in the max clique #
# That only have the clique members in common.               #

[
  #               For pairs of connected nodes                   #
  ( $conn | keys[] ) as $a | $conn[$a][] as $b | select($a < $b) |
  #             Get the list of nodes in common                  #
      [$a,$b] + ($conn[$a] - ($conn[$a]-$conn[$b])) | unique
]

# From largest size find the first where all the nodes in common #
#    are interconnected -> all(connections ⋂ shared == shared)   #
| sort_by(-length)
| first (
  .[] | select( . as $cb |
    [
        $cb[] as $c
      | ( [$c] + $conn[$c] | sort )
      | ( . - ( . - $cb) ) | length
    ] | unique | length == 1
  )
)

else # Do strict max clique check #

# Example of loose failure:
# 0-1 0-2 0-3 0-4 0-5 1-2 1-3 1-4 1-5
# 2-3 2-4 2-5 3-4 3-5 4-5 a-0 a-1 a-2
# a-3 b-2 b-3 b-4 b-5 c-0 c-1 c-4 c-5

def bron_kerbosch1($R; $P; $X; $cliques):
  if ($P|length) == 0 and ($X|length) == 0 then
    if ($R|length) > 2 then
      {cliques: ($cliques + [$R|sort])}
    end
  else
    reduce $P[] as $v ({$R,$P,$X,$cliques};
      .cliques = bron_kerbosch1(
        .R - [$v] + [$v]     ; # R ∪ {v}
        .P - (.P - $conn[$v]); # P ∩ neighbours(v)
        .X - (.X - $conn[$v]); # X ∩ neighbours(v)
           .cliques
      )    .cliques    |
      .P = (.P - [$v]) |       # P ∖ {v}
      .X = (.X - [$v] + [$v])  # X ∪ {v}
    )
  end
;

bron_kerbosch1([];$conn|keys;[];[]).cliques | max_by(length)

end

| join(",") # Output password

[–] [email protected] 3 points 1 day ago

thanksI've probably learned that term at some point, so thanks for naming it. That made me realise my algorithm was too thicc and could just be greedy.

[–] [email protected] 3 points 2 days ago* (last edited 2 days ago)

23-2Leaving something to run for 20-30 minutes expecting nothing and actually getting a valid and correct result: new positive feeling unlocked.

Now to find out how I was ideally supposed to solve it.

[–] [email protected] 3 points 2 days ago

day 23

this is one of those days when it’s all about the right term to google right