#!/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

# Relevant portion
# oneCycle expects an array, of array of chars (3x3 eg: [[".","#","."],[".",".","."],["O",".","#"]])
def oneCycle:
  # Tilt UP          = T . MAP(scan) . T
  # Rotate           = T . MAP(reverse)
  # Titl UP . Rotate = T . MAP(scan) . Map(reverse) | T . T = Identity
  def tilt_up_rotate:
      transpose          # Gets subgroups    # Within each group,
                         # starring with "#" # In order 1 "#", x "O", y "." 
    | map( ("#" + add) | [ scan("#[^#]*")    | ["#", scan("O"), scan("\\.")] ] | add[1:])
    | map(reverse)
  ;
  # Tilt   North,            West,           South,            East
  tilt_up_rotate | tilt_up_rotate | tilt_up_rotate | tilt_up_rotate
;

JQ does allow some nice sortcuts sometimes, again transpose is nice to have.

Further cleaned up version: https://github.com/zogwarg/advent-of-code/blob/main/2023/jq/12-b.jq

Also lost a fair amount of time not not noticing that the sequence should be joined with "?" not with "". (that'll teach me to always run on the example before the full input, when execution time is super long).

Execution time: 17m10s (without memoization a single row was taking multiple minutes, and there's 1000 rows ^^...)

EDIT: see massive improvement by running in parallel in reply.

I substituted the rows/columns, with multiplication by the expansion rate if they were all numbers. And then for each galaxy pair do a running sum by going “down” the “right” and adding the distance for each row and column crossed.

https://github.com/zogwarg/advent-of-code/blob/main/2023/jq/11-b.jq

transpose is nice to have in that approach.

#!/usr/bin/env jq -n -R -f
[
  # For each line, get numbers eg: [ [1,2,3] ]
  inputs / " " | map(tonumber) | [ . ] |

  # Until latest row is all zeroes
  until (.[-1] | [ .[] == 0] | all;
   . += [
     # Add next row, where for element(i) = prev(i+1) - prev(i)
     [ .[-1][1:] , .[-1][0:-1] ] | transpose | map(.[0] - .[1])
    ]
  )
  # Get extrapolated previous element for first row
  |  [ .[][0] ] | reverse | reduce .[] as $i (0; $i - . )
]

# Output sum of extapolations for all lines
| add

I'm pretty sure you could make this one line and unreadable ^^.

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

# Get LR instructions
( input / "" | map(if . == "L" then 0 else 1 end )) as $LR |
( $LR | length ) as $l |

# Make map {"AAA":["BBB","CCC"], ...}
(
  [
    inputs | select(.!= "") | [ scan("[A-Z]{3}") ] | {(.[0]): .[1:]}
  ] | add
) as $map |

# List primes for GCM test / factorization
[
  2, 3, 5, 7, 11, 13, 17, 19,
  23, 29, 31, 37, 41, 43, 47,
  53, 59, 61, 67, 71, 73, 79,
  83, 89, 97
] as $primes |

reduce (
  $map | keys[] | select(test("..A")) | { s: 0, i: 0, c: .} |

  # For each "..A" starting position
  # Produce visited [ "KEY", pos mod $l ], until loop is detected
  until (.i as $i | .[.c] // [] | contains([$i]);
    .s as $s | .i as $i | .c as $c        |
    $map[$c][$LR[$i]] as $next            | # Get next KEY
    .[$c] = (( .[$c] // [ $s ] ) + [$i] ) | # Append ( .s ≡ $l ) to array for KEY (first = .s non mod)
    .s = ( $s + 1 )  | .i = (.s % $l )    | # Update cursors, for next iteration
    .c = $next
  )
  | .[.c][0] as $start_loop_idx | (.s - $start_loop_idx) as $loop_size
  | [ to_entries[] | select(.key[-1:] == "Z") ]
  | if (
      length != 1                                           # Only one ..Z per loop
      or ( .[0].value[0] != $loop_size )                    # First ..Z idx = loop size
      or ( [ .[0].value[0] / $l ] | inside($primes) | not ) # loop_size = ( prime x $l )
      or ( .[0].value[0] / $l  > $l )                       # GCM(loop_sizes) = $l
    ) then "Input does not fit expected pattern" | halt_error else
      # Under these conditions, synched positions of ..Zs happen at:
      # LCM = Π(loop_size_i / GCM) * GCM

      # loop_size_i / GCM
      .[0].value[0] / $l
    end
) as $i (1; . * $i)

# Output LCM = first step where, all ghosts are on "..Z" nodes
| . * $l