this post was submitted on 01 Dec 2023
17 points (100.0% liked)

NotAwfulTech

358 readers
1 users here now

a community for posting cool tech news you don’t want to sneer at

non-awfulness of tech is not required or else we wouldn’t have any posts

founded 1 year ago
MODERATORS
 

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.

you are viewing a single comment's thread
view the rest of the comments
[–] [email protected] 2 points 10 months ago* (last edited 10 months ago) (2 children)

Day 18: Lavaduct Lagoon

[Language: jq]https://github.com/zogwarg/advent-of-code/blob/main/2023/jq/18-b.jq

Satisfyingly short (in lines, not in time writing) some of the longer part is hexadecimal parsing, that doesn't come natively in JQ, I started doing polygon math from part 1, and what took me the longest was properly handling the area contributed by the perimeter. (I toyed with trying very annoying things like computing the outmost vertex at each turn, which is complicated by the fact that you don't initially know which way the digger is turning, and needing previous and next point to disambiguate).

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

reduce (
  # Produce stream of the vertices, for the position of the center
  foreach (
    # From hexadecimal representation
    # Get inputs as stream of directions = ["R", 5]
    inputs | scan("#(.+)\\)") | .[0] / ""
    | map(
        if tonumber? // false then tonumber
        else {"a":10,"b":11,"c":12,"d":13,"e":14,"f":15}[.] end
      )
    | [["R","D","L","U"][.[-1]], .[:-1]]
    | .[1] |= (
      # Convert base-16 array to numeric value.
      .[0] * pow(16;4) +
      .[1] * pow(16;3) +
      .[2] * pow(16;2) +
      .[3] * 16 +
      .[4]
    )
  ) as $dir ([0,0];
    if   $dir[0] == "R" then .[0] += $dir[1]
    elif $dir[0] == "D" then .[1] += $dir[1]
    elif $dir[0] == "L" then .[0] -= $dir[1]
    elif $dir[0] == "U" then .[1] -= $dir[1]
    end
  )
  # Add up total area enclosed by path of center
  # And up the are of the perimeter, perimeter * 1/2 + 1
) as [$x, $y] ( #
  {prev: [0,0], area: 0, perimeter_area: 1  };

  # Adds positve rectangles
  # Removes negative rectangles
  .area += ( $x - .prev[0] ) * $y |

  # Either Δx or Δy is 0, so this is safe
  .perimeter_area += (($x - .prev[0]) + ($y - .prev[1]) | abs) / 2 |

  # Keep current position for next vertex
  .prev = [$x, $y]
)

# Output total area
| ( .area | abs ) + .perimeter_area

Day 19: Aplenty

[Language: jq]https://github.com/zogwarg/advent-of-code/blob/main/2023/jq/19-b.jq

Satisfyingly very well suited to JQ once you are used to the stream, foreach(init; mod; extract) and recurse(exp) [where every output item of exp as a stream is fed back into recurse] operators. It's a different way of coding but has a certain elegance IMO. This was actually quick to implement, along with re-using the treating a range as a primitive approach of the seeds-to-soil day.

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

inputs / "\n\n"

# Parse rules
| .[0] / "\n"
| .[] |= (
  scan("(.+){(.+)}")
  | .[1] |= (. / ",")
  | .[1][] |= capture("^((?<reg>.)(?<op>[^\\d]+)(?<num>\\d+):)?(?<to>[a-zA-Z]+)$")
  | ( .[1][].num | strings ) |= tonumber
  | {key: .[0], value: (.[1]) }
) | from_entries as $rules |

# Split part ranges into new ranges
def split_parts($part; $rule_seq):
  # For each rule in the sequence
  foreach $rule_seq[] as $r (
    # INIT = full range
    {f:$part};

    # OPERATE =
    # Adjust parts being sent forward to next rule
    if $r.reg == null then
      .out = [ .f , $r.to ]
    elif $r.op == "<" and .f[$r.reg][0] < $r.num then
      ([ .f[$r.reg][1], $r.num - 1] | min ) as $split |
      .out = [(.f | .[$r.reg][1] |= $split ), $r.to ] |
      .f[$r.reg][0] |= ($split + 1)
    elif $r.op == ">" and .f[$r.reg][1] > $r.num then
      ([ .f[$r.reg][0], $r.num + 1] | max ) as $split |
      .out = [(.f | .[$r.reg][0] |= $split), $r.to ]  |
      .f[$r.reg][1] |= ($split - 1)
    end;

    # EXTRACT = parts sent to other nodes
    # for recursion call
    .out | select(all(.[0][]; .[0] < .[1]))
  )
;

[ # Start with full range of possible sings in input = "in"
  [ {x:[1,4000],m:[1,4000],a:[1,4000],s:[1,4000]} , "in" ] |

  # Recusively split musical parts, into new ranges objects
  recurse(
    if .[1] == "R" or .[1] == "A" then
      # Stop recursion if "Rejected" or "Accepted"
      empty
    else
      # Recursively split
      split_parts(.[0];$rules[.[1]])
    end
    # Keep only part ranges in "Accepted" state
  ) | select(.[1] == "A") | .[0]

  # Total number if parts in each object is the product of the ranges
  | ( 1 + .x[1] - .x[0] ) *
    ( 1 + .m[1] - .m[0] ) *
    ( 1 + .a[1] - .a[0] ) *
    ( 1 + .s[1] - .s[0] )
  # Sum total number of possibly accepted musical parts
] | add

EDIT: Less-thans and greater-thans replaced by fullwidth version, because lemmy is a hungry little goblin.

[–] [email protected] 3 points 10 months ago

Nice!Also, kudos for working with polygon area from the start. I was too invested in reusing my code as discussed elsewhere, but I came around in the end.

[–] [email protected] 3 points 10 months ago

19 was a real pain in dart.