day3: lisp

2015/days/03/walk.lisp

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+;; Day 3: Perfectly Spherical Houses in a Vacuum
+;;
+;; Part 1: How many houses recieve at least one present?
+
+
+(defun move (char)
+  (cond
+    ((equal char #\>)
+     (list 1 0))
+    ((equal char #\^)
+     (list 0 -1))
+    ((equal char #\<)
+     (list -1 0))
+    ((equal char #\v)
+     (list 0 1))
+    (t nil)
+  ))
+
+(defparameter *houses* (make-hash-table :test 'equal))
+
+(defparameter visited-houses-counter 0)
+
+(defun visit (house)
+  (if (gethash house *houses*)
+      "key exist"
+      (progn
+        (setf visited-houses-counter (+ visited-houses-counter 1))
+        (setf (gethash house *houses*) 1))))
+
+
+(defparameter x 0)
+(defparameter y 0)
+
+(visit (list x y))
+
+(defvar walk)
+
+(defun make-move (char)
+  (progn
+  (setq walk (move char))
+  (setf x (+ x (nth 0 walk)))
+  (setf y (+ y (nth 1 walk)))
+  (visit (list x y))))
+
+(with-open-file (in "./data/input")
+  (do ((c (read-char in)
+             (read-char in nil 'the-end)))
+      ((not (characterp c)))
+    (make-move c)))
+
+(print visited-houses-counter)