refactor advent of code 2023 day 04 from c to racket

1 files changed, 35 insertions, 0 deletions

diff --git a/advent-of-code/2023/04/1.rkt b/advent-of-code/2023/04/1.rkt
new file mode 100644
index 0000000..30ea62f
--- /dev/null
+++ b/advent-of-code/2023/04/1.rkt
@@ -0,0 +1,35 @@
+#lang racket
+
+(require "../lib/obj.rkt")
+
+(define (get-lines fp)
+  (let loop ((lines '()))
+    (define l (read-line fp))
+    (if (eof-object? l)
+      (reverse lines)
+      (loop (cons l lines)))))
+
+(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 (point card)
+  (define wins (length (filter (lambda (x) (member x (card 'win-nums))) (card 'nums))))
+  (if (= wins 0)
+    0
+    (expt 2 (- wins 1))))
+
+(apply + (map point (map parse-card lines)))