From b4d5abe1f24a7ce44f192b6d25fe738e7dba2323 Mon Sep 17 00:00:00 2001
From: haskal <haskal@awoo.systems>
Date: Tue, 22 Dec 2020 00:35:55 -0500
Subject: [PATCH] day 22: bad solution

---
 22.rkt | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 22.rkt

diff --git a/22.rkt b/22.rkt
new file mode 100644
index 0000000..d523c30
--- /dev/null
+++ b/22.rkt
@@ -0,0 +1,80 @@
+#lang curly-fn racket
+
+(require "scripts/aoc.rkt")
+
+;; solution for day 22
+  (define (score cards)
+    (for/sum ([card (in-list cards)] [mult (in-range (length cards) 0 -1)])
+      (* card mult)))
+
+  (define (play p1 p2)
+    (cond
+      [(empty? p1) (score p2)]
+      [(empty? p2) (score p1)]
+      [else
+       (define p1-card (first p1))
+       (define p2-card (first p2))
+       (cond
+        [(> p1-card p2-card) (play (append (rest p1) (list p1-card p2-card)) (rest p2))]
+        [else (play (rest p1) (append (rest p2) (list p2-card p1-card)))])]))
+
+(define (part1 input)
+  (match-define (list p1 p2) input)
+
+  (play p1 p2))
+
+
+(define (part2 input)
+  (match-define (list p1 p2) input)
+
+  (define memo (make-hash))
+  (define (do-memo level p1 p2)
+    (hash-update! memo level (lambda (x) (set-add x (list p1 p2))) (set)))
+
+  (define (play/recur p1 p2 [level 0])
+    ; (printf "~a ~a\n" p1 p2)
+    (cond
+      [(set-member? (hash-ref memo level (set)) (list p1 p2)) (cons 'p1 (score p1))]
+      [(empty? p1) (cons 'p2 (score p2))]
+      [(empty? p2) (cons 'p1 (score p1))]
+      [else
+       (define p1-card (first p1))
+       (define p1-rest (rest p1))
+       (define p2-card (first p2))
+       (define p2-rest (rest p2))
+       (cond
+        [(and (>= (length p1-rest) p1-card)
+              (>= (length p2-rest) p2-card))
+         (match-define (cons winner score)
+           (play/recur (take p1-rest p1-card) (take p2-rest p2-card) (add1 level)))
+         ; (printf "submatch ~a\n" winner)
+         (do-memo level p1 p2)
+         (if (symbol=? winner 'p1)
+           (play/recur (append p1-rest (list p1-card p2-card)) p2-rest level)
+           (play/recur p1-rest (append p2-rest (list p2-card p1-card)) level))]
+        [(> p1-card p2-card)
+         (do-memo level p1 p2)
+         (play/recur (append p1-rest (list p1-card p2-card)) p2-rest level)]
+        [else
+          (do-memo level p1 p2)
+           (play/recur p1-rest (append p2-rest (list p2-card p1-card)) level)])]))
+
+  (cdr (play/recur p1 p2)))
+
+;; parse input file
+(define (parse fname)
+  (match-define (list p1 p2) (string-split (file->string fname) "\n\n"))
+  (list
+    (map string->number (rest (string-split p1 "\n")))
+    (map string->number (rest (string-split p2 "\n")))))
+
+(module+ test
+  (require rackunit)
+  ;; tests here
+  (displayln "no tests :("))
+
+(module+ main
+  (define input (parse "inputs/22"))
+  (answer 22 1 (time (part1 input)))
+  (answer 22 2 (time (part2 input)))
+  (displayln "meow"))