Challenge with images: Racket: `it's showtime`

8.rkt

@@ -0,0 +1,50 @@
+#lang racket
+
+(define input (for/list ([str (string-trim (file->string "input.8.txt"))])
+                (string->number (string str))))
+
+(define width 25)
+(define height 6)
+(define pixels-per-layer (* width height))
+
+(define (make-chunks lst n)
+  (cond [(empty? lst) '()]
+        [else (cons (take lst n) (make-chunks (drop lst n) n))]))
+
+(define layers (make-chunks input pixels-per-layer))
+
+(define (count-occur lst what)
+  (length (filter ((curry =) what) lst)))
+
+(define (lowest-zeroes chunks)
+  (cond [(empty? (rest chunks)) (first chunks)]
+        [else
+         (let ([this (first chunks)]
+               [next (lowest-zeroes (rest chunks))])
+           (if (< (count-occur this 0) (count-occur next 0))
+               this
+               next))]))
+
+(define lowest-zero-layer (lowest-zeroes layers))
+
+;; Part 1
+(* (count-occur lowest-zero-layer 1) (count-occur lowest-zero-layer 2))
+
+(require 2htdp/image)
+
+(define pixel-size 16)
+(define colors '(black white transparent))
+
+(define (render-pixel code)
+  (rectangle pixel-size pixel-size 'solid (list-ref colors code)))
+
+(define (render-layer layer)
+  (define (render-row row)
+    (apply beside (map render-pixel row)))
+  (apply above (map render-row (make-chunks layer width))))
+
+(define base (empty-scene (* pixel-size width) (* pixel-size height)))
+(define decoded-image
+  (foldr overlay base (map render-layer layers)))
+;; Part 2
+(frame decoded-image)