hg.stevelosh.com > advent

src/2020/days/day-13.lisp @ 2848a4548adf 

2023/01 and 2022/01

Also start porting my test data to the new account, since Twitter imploded and
apparently it's impossible for a website to store a goddamn username and
password in The Year of Our Lord 2023 so everyone just outsources auth all
the time, ugh.
author Steve Losh <steve@stevelosh.com>
date Fri, 01 Dec 2023 11:05:43 -0500
parents 0b68f84e44ae
children (none) 
(advent:defpackage* :advent/2020/13)
(in-package :advent/2020/13)

(defun parse (stream)
    (cons (parse-integer (read-line stream))
            (_ (read-line stream)
              (str:split "," _)
              (remove "x" _ :test #'string=)
              (mapcar #'parse-integer _))))

(defun part1 (n buses)
  (iterate (for b :in buses)
           (for wait = (- (mod n (- b))))
           (finding (* b wait) :minimizing wait)))

(define-problem (2020 13) (data parse) (174)
  (destructuring-bind (n . buses) data
      (values (part1 n buses))))


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