Day 4 Part 1

chicken.org

@@ -2138,14 +2138,15 @@ For that, I first create the pattern for a card.
 #+begin_src scheme :tangle day4.scm
   (define card-irregex
     '(: bol
-        (* " ")
-        "Card "
-        (submatch-named card-no (+ (/ #\0 #\9)))
+        (* whitespace)
+        "Card"
+        (+ whitespace)
+        (submatch-named card-no (+ numeric))
         ": "
-        (submatch-named winning-numbers-str (+ (or (/ #\0 #\9) #\space))
+        (submatch-named winning-numbers-str (+ (or numeric whitespace)))
         " | "
-        (submatch-named card-numbers-str (+ (or (/ #\0 #\9) #\space)))
-        eol)))
+        (submatch-named card-numbers-str (+ (or numeric whitespace)))
+        eol))
 #+end_src
 
 The pattern is then used to extract every scratch card which is then being parsed in a fold
@@ -2160,9 +2161,9 @@ statement.
          (make-scratchcard
           (string->number (irregex-match-substring match 'card-no))
           (map string->number
-               (string-split (irregex-match-substring match 'winning-numbers-str) " "))
+               (string-split (irregex-match-substring match 'winning-numbers-str)))
           (map string->number
-               (string-split (irregex-match-substring match 'card-numbers-str) " "))
+               (string-split (irregex-match-substring match 'card-numbers-str)))
           '())
          seed))
       '() input-str))
@@ -2178,10 +2179,13 @@ name ends with an ~!~.
 #+NAME: day4-part1-card-matching
 #+begin_src scheme :tangle day4.scm
   (define (calc-card-matches card)
+    (print "calculating matches for " (scratchcard-id card))
     (let ((winning-nums (scratchcard-winning-numbers card))
           (card-nums (scratchcard-card-numbers card)))
       (for-each (lambda (card-num)
+                  (print "\tCard number: " card-num)
                   (when (foldl (lambda (matches? winning-num)
+                                 (print "\t\tWinning number: " winning-num)
                                  (or matches?
                                      (= card-num winning-num)))
                                #f winning-nums)
@@ -2209,8 +2213,9 @@ And now, we can put everything together and sum up the points:
 #+begin_src scheme
   (foldl
    (lambda (sum card)
+     (calc-card-matches card)
      (+ sum
-        (card-points (calc-card-matches card))))
+        (card-points card)))
    0 (input->cards input))
 #+end_src
 
@@ -2226,6 +2231,9 @@ And now, we can put everything together and sum up the points:
   <<day4-part1-calc>>
 #+end_src
 
+#+RESULTS: day4-part1-calc-full
+: 23441
+
 #+begin_src scheme :noweb yes :exports none :tangle day4.scm
   (define (calc-part-1)
     <<day4-part1-calc>>)
@@ -2233,6 +2241,59 @@ And now, we can put everything together and sum up the points:
 
 ** Part Two
 
+*** Quest
+
+Just as you're about to report your findings to the Elf, one of you realizes that the rules have
+actually been printed on the back of every card this whole time.
+
+There's no such thing as "points". Instead, scratchcards only cause you to *win more scratchcards*
+equal to the number of winning numbers you have.
+
+Specifically, you win copies of the scratchcards below the winning card equal to the number of
+matches. So, if card 10 were to have 5 matching numbers, you would win one copy each of cards 11,
+12, 13, 14, and 15.
+
+Copies of scratchcards are scored like normal scratchcards and have the *same card number* as the
+card they copied. So, if you win a copy of card 10 and it has 5 matching numbers, it would then win
+a copy of the same cards that the original card 10 won: cards 11, 12, 13, 14, and 15. This process
+repeats until none of the copies cause you to win any more cards. (Cards will never make you copy a
+card past the end of the table.)
+
+This time, the above example goes differently:
+
+#+begin_example
+Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53
+Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19
+Card 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1
+Card 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83
+Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36
+Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11
+#+end_example
+
+- Card 1 has four matching numbers, so you win one copy each of the next four cards: cards 2, 3, 4,
+  and 5.
+- Your original card 2 has two matching numbers, so you win one copy each of cards 3 and 4.
+- Your copy of card 2 also wins one copy each of cards 3 and 4.
+- Your four instances of card 3 (one original and three copies) have two matching numbers, so you
+  win *four* copies each of cards 4 and 5.
+- Your eight instances of card 4 (one original and seven copies) have one matching number, so you
+  win *eight* copies of card 5.
+- Your fourteen instances of card 5 (one original and thirteen copies) have no matching numbers and
+  win no more cards.
+- Your one instance of card 6 (one original) has no matching numbers and wins no more cards.
+
+Once all of the originals and copies have been processed, you end up with *=1=* instance of card 1,
+*=2=* instances of card 2, *=4=* instances of card 3, *=8=* instances of card 4, *=14=* instances of
+card 5, and *=1=* instance of card 6. In total, this example pile of scratchcards causes you to
+ultimately have *=30=* scratchcards!
+
+Process all of the original and copied scratchcards until no more scratchcards are won. Including
+the original set of scratchcards, *how many total scratchcards do you end up with?*
+
+*** Puzzle Solution
+
+WIP...
+
 ** Puzzle Input
 
 #+NAME: day4-input