X-Git-Url: http://git.jkinsey.net/?p=adventofcode2020.git;a=blobdiff_plain;f=src%2Futilities.lisp;fp=src%2Futilities.lisp;h=ce9aa6d39ce67b27c0608dda35c3adf23e5e18b9;hp=6e0ca47d84f02726cd4becea7d1db06bc557b60d;hb=646650211622736cd7f85f69cdad3a2899cfe153;hpb=955fe99709e9fd567d2a296e8eee7a1c459ea439

diff --git a/src/utilities.lisp b/src/utilities.lisp
index 6e0ca47..ce9aa6d 100644
--- a/src/utilities.lisp
+++ b/src/utilities.lisp
@@ -20,6 +20,11 @@
         (wrap-A (mapcar #'list A)))
     (reduce helper C :initial-value (funcall helper wrap-A B))))
 
+(defun manhattan-distance (a b)
+  (destructuring-bind ((ax ay) (bx by)) (list a b)
+    (+ (abs (- ax bx))
+       (abs (- ay by)))))
+
 (def-suite util)
 (in-suite util)