Initial commit

2021/day06/day06.scm

@@ -0,0 +1,36 @@
+(import (chicken io)
+	srfi-1
+	srfi-42
+	srfi-152)
+
+(define (read-input #!optional (port (current-input-port)))
+  (map string->number (string-split (read-line port) ",")))
+
+(define (count-fishes in)
+  (define c (make-list 9 0))
+  (do-ec (: x in)
+	 (set! (list-ref c x) (add1 (list-ref c x))))
+  c)
+
+(define (simulate counts days)
+  (if (= 0 days)
+      (take counts 9)
+      (let ((n (car counts)))
+	(set! (list-ref counts 7) (+ n (list-ref counts 7)))
+	(simulate (cdr counts) (- days 1)))))
+
+(define (total-fishes counts days)
+  (apply + (take (simulate (apply circular-list counts) days) 9)))
+
+(let* ((in '(3 4 3 1 2))
+       (counts (count-fishes in)))
+  (print "Test:")
+  (print (total-fishes counts 18))
+  (print (total-fishes counts 80))
+  (print (total-fishes counts 256)))
+
+(print)
+(let* ((in (read-input))
+       (counts (count-fishes in)))
+  (print (total-fishes counts 80))
+  (print (total-fishes counts 256)))