2019/04
author |
Steve Losh <steve@stevelosh.com> |
date |
Wed, 04 Dec 2019 12:04:52 -0500 |
parents |
4835e36925af |
children |
(none) |
(defpackage :advent/2017/11 #.cl-user::*advent-use*)
(in-package :advent/2017/11)
;; https://www.redblobgames.com/grids/hexagons/#coordinates
(defun coord+ (c1 c2)
(map 'vector #'+ c1 c2))
(defun coord- (c1 c2)
(map 'vector #'- c1 c2))
(defun distance (c1 &optional (c2 #(0 0 0)))
(/ (reduce #'+ (coord- c1 c2) :key #'abs) 2))
(define-problem (2017 11) (data read-comma-separated-values) (773 1560)
(iterate
(with pos = #(0 0 0))
(for direction :in (mapcar #'ensure-keyword data))
(setf pos (coord+ pos (delta direction)))
(maximizing (distance pos) :into furthest)
(finally (return (values (distance pos) furthest)))))