1 files changed, 49 insertions, 0 deletions
diff --git a/aoc2023-other/day-07/day-07.rkt b/aoc2023-other/day-07/day-07.rkt
new file mode 100644
index 0000000..67dc212
--- /dev/null
+++ b/aoc2023-other/day-07/day-07.rkt
@@ -0,0 +1,49 @@
+#lang racket
+
+(require advent-of-code
+         threading)
+
+(struct hand (cards wager) #:transparent)
+
+(define/match (card->int card)
+  [((? char-numeric?)) (~> card string string->number)]
+  [(#\A) 14]
+  [(#\K) 13]
+  [(#\Q) 12]
+  [(#\J) 11]
+  [(#\T) 10]
+  [(#\*) 1])
+
+(define (parse-hand str)
+  (match-define (list card-str wager-str) (string-split str))
+  (define cards (~> card-str string->list (map card->int _)))
+  (define wager (~> wager-str string->number))
+  (hand cards wager))
+
+(define input (~> (open-aoc-input (find-session) 2023 7 #:cache #true) port->lines))
+
+(define (identify-hand h)
+  (define freqs (~> h hand-cards (sort <) (group-by identity _) (map length _)))
+  (match freqs
+    [(list-no-order 5) 8]
+    [(list-no-order 1 4) 7]
+    [(list-no-order 2 3) 6]
+    [(list-no-order 1 1 3) 5]
+    [(list-no-order 1 2 2) 4]
+    [(list-no-order 1 1 1 2) 3]
+    [(list-no-order 1 1 1 1 1) 2]))
+
+(define (compare-first-card cs1 cs2)
+  (if (= (first cs1) (first cs2))
+      (compare-first-card (rest cs1) (rest cs2))
+      (< (first cs1) (first cs2))))
+
+(define (compare-hands h1 h2)
+  (define rank1 (identify-hand h1))
+  (define rank2 (identify-hand h2))
+  (if (= rank1 rank2) (compare-first-card (hand-cards h1) (hand-cards h2)) (< rank1 rank2)))
+
+;; part 1
+
+(for/sum ([(h i) (in-indexed (~> input (map parse-hand _) (sort compare-hands)))])
+         (* (add1 i) (hand-wager h)))