Initial commit

2018/day03/day03.ss

@@ -0,0 +1,30 @@
+(import :gerbil/gambit/ports)
+(import :std/pregexp)
+(import :std/iter)
+
+(export main)
+
+(def (claim-area! fabric claim)
+  (match claim
+    ([id x y w h] (for* ((i (in-range x w))
+			 (j (in-range y h)))
+		    (hash-update! fabric [i j] (lambda (l) (cons id l)) [])))))
+
+(def (non-overlapping-claim fabric)
+  (def overlapping (make-hash-table))
+  (hash-for-each (lambda (k v) (for ((id v)) (hash-put! overlapping id #t))) fabric)
+  (hash-for-each (lambda (k v) (when (< 1 (length v))
+				 (for ((id v)) (hash-put! overlapping id #f))))
+		 fabric)
+  (hash->list overlapping)
+  (hash-find (lambda (k v) (if v k #f)) overlapping))
+
+(def (main . args)
+  (def claims-str (call-with-input-file "input.txt" (lambda (p) (read-all p read-line))))
+  (def claims (map (lambda (x) (filter-map string->number (pregexp-split "[ #@,:x]" x))) claims-str))
+  (def fabric (make-hash-table))
+  (for ((claim claims))
+    (claim-area! fabric claim))
+  (displayln (hash-fold (lambda (k v acc) (if (> (length v) 1) (1+ acc) acc)) 0 fabric))
+
+  (displayln (non-overlapping-claim fabric)))