1 files changed, 47 insertions, 0 deletions
diff --git a/04/2.rkt b/04/2.rkt
new file mode 100644
index 0000000..97977ec
--- /dev/null
+++ b/04/2.rkt
@@ -0,0 +1,47 @@
+#lang racket
+
+(require "../lib/utils.rkt")
+(require "../lib/obj.rkt")
+
+(define fp (open-input-file "input"))
+
+(define lines (get-lines fp))
+
+(define (strip-head s)
+  (string-trim (cadr (string-split s ":"))))
+
+(set! lines (map strip-head lines))
+
+(define make-card (obj-maker 'win-nums 'nums))
+
+(define (parse-card s)
+  (define lst (string-split s "|"))
+  (define win-nums (map string->number (string-split (car lst))))
+  (define nums (map string->number (string-split (cadr lst))))
+  (make-card win-nums nums))
+
+(define cards (map parse-card lines))
+
+(define card-count (make-vector (length cards) 1))
+
+(define (win-count card)
+  (length (filter (λ (x) (member x (card 'win-nums))) (card 'nums))))
+
+(define card-vec (list->vector cards))
+
+(let loop ((i 0))
+  (if (>= i (vector-length card-count))
+      (void)
+      (let ()
+        (define win-cnt (win-count (vector-ref card-vec i)))
+        (let loop ((j (+ i 1)))
+          (if (or (>= j (vector-length card-count))
+                  (>= j (+ 1 i win-cnt)))
+              (void)
+              (let ()
+                (vector-set! card-count j (+ (vector-ref card-count i)
+                                             (vector-ref card-count j)))
+                (loop (+ 1 j)))))
+        (loop (+ 1 i)))))
+
+(apply + (vector->list card-count))
+\ No newline at end of file