src/2018/days/day-02.lisp @ 77fa6a483e0e
2021/04
author |
Steve Losh <steve@stevelosh.com> |
date |
Sat, 04 Dec 2021 13:11:25 -0500 |
parents |
182bdd87fd9e |
children |
(none) |
(advent:defpackage* :advent/2018/02)
(in-package :advent/2018/02)
(define-problem (2018 2) (data read-lines) (8296 "pazvmqbftrbeosiecxlghkwud")
(values
(let* ((freqs (mapcar #'frequencies data))
(counts (mapcar #'alexandria:hash-table-values freqs)))
(* (count 2 counts :test #'member)
(count 3 counts :test #'member)))
;; just brute force it
(multiple-value-bind (a b)
(iterate
(for (a . remaining) :on data)
(for b = (find 1 remaining :key (curry #'hamming-distance a)))
(when b
(return (values a b))))
(let ((i (mismatch a b)))
(str:concat (subseq a 0 i)
(subseq a (1+ i)))))))