src/2017/days/day-01.lisp @ 0a241f64eebb
2016/01
author |
Steve Losh <steve@stevelosh.com> |
date |
Fri, 06 Dec 2019 20:57:40 -0500 |
parents |
cd781337a694 |
children |
182bdd87fd9e |
(defpackage :advent/2017/01 #.cl-user::*advent-use*)
(in-package :advent/2017/01)
(define-problem (2017 1) (data read-line) (1049 1508)
(iterate
(with digits = (map 'vector #'digit-char-p data))
(for digit :in-vector digits)
(for prev :previous digit :initially (aref digits (1- (length digits))))
(for j :modulo (length digits) :from (truncate (length digits) 2))
(for next = (aref digits j))
(when (= digit prev) (sum digit :into part1))
(when (= digit next) (sum digit :into part2))
(finally (return (values part1 part2)))))