Initial commit

2018/day09/day09.ss

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+(import :std/srfi/1)
+
+(export main)
+
+(def (rotate-right deque k)
+  (def left (car deque))
+  (def right (cadr deque))
+  (if (= k 0)
+    deque
+    (if (null? right)
+      (rotate-right [[] (reverse left)] k)
+      (rotate-right [(cons (car right) left) (cdr right)] (1- k)))))
+
+(def (rotate-left deque k)
+  (def left (car deque))
+  (def right (cadr deque))
+  (if (= k 0)
+    deque
+    (if (null? left)
+      (rotate-left [(reverse right) '()] k)
+      (rotate-left [(cdr left) (cons (car left) right)] (1- k)))))
+
+(def (deque-car deque)
+  (match deque
+    ([left right] (car right))))
+
+(def (deque-cdr deque)
+  (match deque
+    ([left right] [left (cdr right)])))
+
+(def (deque-cons x deque)
+  (match deque
+    ([left right] [left (cons x right)])))
+
+(def (display-deque deque)
+  (displayln (reverse (car deque)) " " (cadr deque)))
+
+(def (play circle marbles scores player)
+  ;; (display-deque circle)
+  (match marbles
+    ([] scores)
+    ([marble . rest]
+     (def new-player (remainder (1+ player) (vector-length scores)))
+     (if (= 0 (remainder marble 23))
+       (let ((new-circle (rotate-left circle 7)))
+	 (vector-set! scores player (+ marble (deque-car new-circle) (vector-ref scores player)))
+	 (play (deque-cdr new-circle) (cdr marbles) scores new-player))
+       (let ((new-circle (deque-cons marble (rotate-right circle 2))))
+	 (play new-circle (cdr marbles) scores new-player))))))
+
+(def (marbles-game n-players last-marble)
+  (apply max (vector->list (play  [[] [0]] (iota last-marble 1) (make-vector n-players 0) 0))))
+
+(def (main (n-players "9") (last-marble "25") . args)
+  (displayln (marbles-game 9 25))
+  (displayln (marbles-game 10 1618))
+  (displayln (marbles-game 13 7999))
+  (displayln (marbles-game 17 1104))
+  (displayln (marbles-game 21 6111))
+  (displayln (marbles-game 30 5807))
+  (displayln (marbles-game (string->number n-players) (string->number last-marble))))

2018/day09/input.txt

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+463 players; last marble is worth 71787 points