day 21 cleanup

1 files changed, 19 insertions, 33 deletions

diff --git a/2021/day-21/day-21.rkt b/2021/day-21/day-21.rkt
index d2e17b6..46bbbe2 100644
--- a/2021/day-21/day-21.rkt
+++ b/2021/day-21/day-21.rkt
@@ -19,27 +19,21 @@
                [last-turn 0]
                #:result (list (min player-1-score player-2-score) (* 3 last-turn)))
               ([turn-count (in-naturals 1)]
-               [turn current-turn]
+               [turn-for current-turn]
                #:break (or (player-1-score . >= . 1000)
                            (player-2-score . >= . 1000)))
       (define rolls (apply + (stream->list (stream-take dice 3))))
-      (cond
-        [(equal? turn 'player-1)
-         (values (+ player-1-score
-                    (stream-first (stream-tail player-1-track rolls)))
-                 (stream-tail player-1-track rolls)
-                 player-2-score
-                 player-2-track
-                 (stream-tail dice 3)
-                 turn-count)]
-        [(equal? turn 'player-2)
-         (values player-1-score
-                 player-1-track
-                 (+ player-2-score
-                    (stream-first (stream-tail player-2-track rolls)))
-                 (stream-tail player-2-track rolls)
-                 (stream-tail dice 3)
-                 turn-count)]))
+      (match turn-for
+        ['player-1 (define next-track (stream-tail player-1-track rolls))
+                   (values (+ player-1-score (stream-first next-track)) next-track
+                           player-2-score player-2-track
+                           (stream-tail dice 3)
+                           turn-count)]
+        ['player-2 (define next-track (stream-tail player-2-track rolls))
+                   (values player-1-score player-1-track
+                           (+ player-2-score (stream-first next-track)) next-track
+                           (stream-tail dice 3)
+                           turn-count)]))
   (apply * _))
 
 ;; part 2
@@ -52,20 +46,12 @@
     [(p1-score . >= . 21) '(1 0)]
     [(p2-score . >= . 21) '(0 1)]
     [else
-     (for/fold ([p-wins '(0 0)])
+     (for/fold ([wins '(0 0)])
                ([roll (in-list roll-space)])
-       (define move-to (~> p1-start
-                         (+ roll)
-                         sub1
-                         (modulo 10)
-                         add1))
-       (match-define (list p1-wins p2-wins) p-wins)
-       (match-define (list p2-possible-win p1-possible-win)
-         (next-turns p2-score
-                     (+ p1-score move-to)
-                     p2-start
-                     move-to))
-       (list (+ p1-wins p1-possible-win)
-             (+ p2-wins p2-possible-win)))]))
+       (define move-to (add1 (modulo (sub1 (+ roll p1-start)) 10)))
+       (define possible-wins (next-turns p2-score (+ p1-score move-to) p2-start move-to))
+       (list (+ (first wins) (second possible-wins))
+             (+ (second wins) (first possible-wins ))))]))
 
-(~>> (next-turns 0 0 player-1-start player-2-start) (apply max))
\ No newline at end of file
+(~>> (next-turns 0 0 player-1-start player-2-start)
+     (apply max))
\ No newline at end of file