Days 08--12

These days have been done while traveling, so they may be less modular
due to time/phone-screen constraints.

1 files changed, 67 insertions, 0 deletions

diff --git a/day10.scm b/day10.scm
new file mode 100644
index 0000000..516331a
--- /dev/null
+++ b/day10.scm
@@ -0,0 +1,67 @@
+(define-module (day10)
+	       #:use-module (ice-9 rdelim)
+	       #:use-module (srfi srfi-1))
+
+(define (read-input port)
+  (define (iter acc)
+    (define line (read-line port))
+    (if (or (eof-object? line) (string= "" line))
+      (list->typed-array 'u8 2 (reverse acc))
+      (iter (cons (map
+		    (lambda (c) (- (char->integer c) (char->integer #\0)))
+		    (string->list line))
+		  acc))))
+  (iter '()))
+
+(define (dp! inp mp num join cellinit)
+  (define-values (m n) (apply values (array-dimensions inp)))
+  (unless (negative? num)
+   (let iter-row ((i 0))
+     (unless (= i m)
+       (let iter-cell ((j 0))
+	 (unless (= j n)
+	   (when (= num (array-ref inp i j))
+	     (array-set! 
+	       mp
+	       (fold (lambda (di dj acc)
+		       (if (and (array-in-bounds? inp (+ i di) (+ j dj))
+				(= (+ 1 num) (array-ref inp (+ i di) (+ j dj))))
+			 (join
+				  acc (array-ref mp (+ i di) (+ j dj)))
+			 acc))
+		     cellinit
+		     '(1 -1 0 0) '(0 0 1 -1))
+	       i j))
+	   (iter-cell (+ j 1))))
+       (iter-row (+ i 1))))
+   (dp! inp mp (- num 1) join cellinit)))
+
+(define (doit port score join cellinit 9init)
+  (define inp (read-input port))
+  (define-values (m n) (apply values (array-dimensions inp)))
+  (define mp (make-array 0 m n))
+  (define idx 0)
+  (array-map! mp (lambda (s) (if (= s 9) (9init) cellinit)) inp)
+  (dp! inp mp 8 join cellinit)
+  ;(display mp)
+  (let iter-row ((i 0) (acc 0))
+    (if (= i m)
+      acc
+      (iter-row (+ i 1)
+		(let iter-cell ((j 0) (acc acc))
+		  (if (= j n)
+		    acc
+		    (iter-cell (+ j 1)
+			       (+ acc (if (= (array-ref inp i j) 0)
+					(score (array-ref mp i j))
+					0)))))))))
+
+(define (part1 port)
+  (define idx 0)
+  (doit port length (lambda (a b) (lset-union = a b))
+	'()
+(lambda () (set! idx (+ idx 1)) (list idx))))
+
+(define (part2 port)
+  (doit port values + 0 (lambda () 1)))
+