add day 4 solutions

1 files changed, 37 insertions, 0 deletions

diff --git a/4-2.scm b/4-2.scm
new file mode 100755
index 0000000..48517ce
--- /dev/null
+++ b/4-2.scm
@@ -0,0 +1,37 @@
+#!/usr/bin/env -S guile -s
+!#
+(use-modules (ice-9 regex)
+             (ice-9 textual-ports)
+             (srfi srfi-1))
+
+(define (read-lines port)
+  (letrec ((loop (lambda (l ls)
+                   (if (eof-object? l)
+                       ls
+                       (loop (get-line port) (cons l ls))))))
+    (reverse (loop (get-line port) '()))))
+
+(define (split-up nums)
+  (filter (lambda (x) (not (string-null? x))) (string-split nums char-set:whitespace)))
+
+(define (parse line)
+  (let* ((m (string-match " ([0-9]+): ([0-9| ]+) \\| ([0-9| ]+)" line))
+         (winning (split-up (match:substring m 2)))
+         (have (split-up (match:substring m 3)))
+         (shared (filter (lambda (x) (member x winning)) have)))
+    `(,(length shared) . ,1)))
+
+(let* ((port (open-input-file "4.txt"))
+       (lines (read-lines port))
+       (cards (map parse lines)))
+  (close-port port)
+  ;; (while (< index (length cards))
+  ;;   (do ((i 1 (1+ i))) ((> i (cdr (list-ref cards index))))
+  ;;     (set! cards (append cards `(,(assoc (+ (car (list-ref cards index)) i) cards)))))
+  ;;   (set! index (1+ index)))
+  ;; (display (length cards))
+  (do ((i 0 (1+ i))) ((= i (length cards)))
+    (do ((j 1 (1+ j))) ((> j (car (list-ref cards i))))
+      (let ((card (list-ref cards (+ i j))))
+        (list-set! cards (+ i j) `(,(car card) . ,(+ (cdr card) (cdr (list-ref cards i))))))))
+  (display (fold + 0 (map cdr cards))))