copy pasting the rules from last year’s thread:
Rules: no spoilers.
The other rules are made up aswe go along.
Share code by link to a forge, home page, pastebin (Eric Wastl has one here) or code section in a comment.
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4 points
Day 8
Al lot of grid index shuffling these past few days! Not too difficult yet though, will this year be gentler or much harsher later?
Part 2 code in JQ
#!/usr/bin/env jq -n -R -f
[ inputs / "" ] | [.,.[0]|length] as [$H,$W] |
#----- In bound selectors -----#
def x: select(. >= 0 and . < $W);
def y: select(. >= 0 and . < $H);
reduce (
[
to_entries[] | .key as $y | .value |
to_entries[] | .key as $x | .value |
[ [$x,$y],. ] | select(last!=".")
] | group_by(last)[] # Every antenna pair #
| combinations(2) | select(first < last)
) as [[[$ax,$ay]],[[$bx,$by]]] ({};
# Assign linear anti-nodes #
.[ range(-$H;$H) as $i | "\(
[($ax+$i*($ax-$bx)|x), ($ay+$i*($ay-$by)|y)] | select(length==2)
)"] = true
) | length
