Day 4: Scratchcards
Megathread guidelines
- Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
- Code block support is not fully rolled out yet but likely will be in the middle of the event. Try to share solutions as both code blocks and using something such as https://topaz.github.io/paste/ or pastebin (code blocks to future proof it for when 0.19 comes out and since code blocks currently function in some apps and some instances as well if they are running a 0.19 beta)
FAQ
- What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
- Where do I participate?: https://adventofcode.com/
- Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465
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2 points
*
Factor on github (with comments and imports):
: line>cards ( line -- winning-nums player-nums )
":|" split rest
[
[ CHAR: space = ] trim
split-words harvest [ string>number ] map
] map first2
;
: points ( winning-nums player-nums -- n )
intersect length
dup 0 > [ 1 - 2^ ] when
;
: part1 ( -- )
"vocab:aoc-2023/day04/input.txt" utf8 file-lines
[ line>cards points ] map-sum .
;
: follow-card ( i commons -- n )
[ 1 ] 2dip
2dup nth swapd
over + (a..b]
[ over follow-card ] map-sum
nip +
;
: part2 ( -- )
"vocab:aoc-2023/day04/input.txt" utf8 file-lines
[ line>cards intersect length ] map
dup length swap '[ _ follow-card ]
map-sum .
;