1 files changed, 63 insertions, 0 deletions
diff --git a/14/1.rkt b/14/1.rkt
new file mode 100644
index 0000000..79dcefc
--- /dev/null
+++ b/14/1.rkt
@@ -0,0 +1,63 @@
+#lang racket
+
+(require "../lib/utils.rkt")
+
+(define lines
+  (call-with-input-file "input"
+    (λ (fp) (get-lines fp))))
+
+(define mat (list->vector lines))
+
+(define (char-at x y)
+  (string-ref (vector-ref mat y) x))
+
+(define (set-mat! x y c)
+  (string-set! (vector-ref mat y) x c))
+
+(define (move-stone x1 y1 x2 y2)
+  (define t (char-at x1 y1))
+  (set-mat! x1 y1 (char-at x2 y2))
+  (set-mat! x2 y2 t))
+
+(define (find-new-pos x y)
+  (let loop ((new-y y))
+    (if (or (= new-y 0)
+            (not (char=? #\. (char-at x (- new-y 1)))))
+        new-y
+        (loop (- new-y 1)))))
+
+(define height (vector-length mat))
+(define width (string-length (vector-ref mat 0)))
+
+(define (tilt)
+  (let loop ((y 0))
+    (if (>= y height)
+        (void)
+        (let ()
+          (let loop1 ((x 0))
+            (if (>= x width)
+                (void)
+                (let ()
+                  (define c (char-at x y))
+                  (if (char=? #\O c)
+                      (let ()
+                        (define new-y (find-new-pos x y))
+                        (move-stone x y x new-y)
+                        (loop1 (+ 1 x)))
+                      (loop1 (+ 1 x))))))
+          (loop (+ 1 y))))))
+
+(define (count)
+  (let loop ((x 0) (y 0) (sum 0))
+    (if (>= y height)
+        sum
+        (if (>= x width)
+            (loop 0 (+ 1 y) sum)
+            (let ()
+              (define c (char-at x y))
+              (if (char=? c #\O)
+                  (loop (+ 1 x) y (+ sum (- height y)))
+                  (loop (+ 1 x) y sum)))))))
+
+(tilt)
+(count)
+\ No newline at end of file