src/2021/days/day-01.lisp @ 9312a3a851cc
2021/10
author |
Steve Losh <steve@stevelosh.com> |
date |
Fri, 10 Dec 2021 18:14:40 -0800 |
parents |
166414163a73 |
children |
(none) |
(advent:defpackage* :advent/2021/01)
(in-package :advent/2021/01)
(define-problem (2021 1) (data read-numbers) (1754 1789)
(values
(iterate (for d :in (nthcdr 1 data))
(for p :in data)
(counting (> d p)))
;; The window total is a red herring. We only need to count when it
;; increases, and only increases when the number you're adding is larger
;; than the number you're subtracting.
(iterate (for d :in (nthcdr 3 data))
(for p :in data)
(counting (> d p)))))
#; Scratch --------------------------------------------------------------------