1 files changed, 42 insertions, 0 deletions
diff --git a/10.scm b/10.scm
new file mode 100755
index 0000000..15c4b1c
--- /dev/null
+++ b/10.scm
@@ -0,0 +1,42 @@
+#!/usr/bin/env -S guile -s
+!#
+(use-modules (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 (candidates-for type pos)
+  (let ((x (car pos))
+        (y (cdr pos)))
+    (cond ((equal? type #\|) `(,(cons x (1+ y))
+                               ,(cons x (1- y))))
+          ((equal? type #\-) `(,(cons (1+ x) y)
+                               ,(cons (1- x) y)))
+          ((equal? type #\L) `(,(cons x (1- y))
+                               ,(cons (1+ x) y)))
+          ((equal? type #\J) `(,(cons x (1- y))
+                               ,(cons (1- x) y)))
+          ((equal? type #\7) `(,(cons (1- x) y)
+                               ,(cons x (1+ y))))
+          ((equal? type #\F) `(,(cons x (1+ y))
+                               ,(cons (1+ x) y)))
+          ((equal? type #\S) `(,(cons x (1+ y))
+                               ,(cons x (1- y))
+                               ,(cons (1+ x) y)
+                               ,(cons (1- x) y)))
+          ((equal? type #\.) '()))))
+
+(let* ((port (open-input-file "10s.txt"))
+       (lines (read-lines port))
+       (candidates '((0 . 2)))
+       (seen '()))
+  (close-port port)
+  (while (not (null? candidates))
+    (set! candidates (append! (cdr candidates) (filter (lambda (x) (member x seen)) (candidates-for (string-ref (list-ref lines (cdar candidates)) (caar candidates)) (car candidates)))))
+    (display candidates)
+    (newline)))