advent-of-code/2023/1/main-2.lisp
2023-12-01 22:41:12 -08:00

49 lines
1.5 KiB
Common Lisp

(defpackage #:aoc-2023/1.2
(:use #:cl)
(:export #:main))
(in-package #:aoc-2023/1.2)
(defparameter *numbers* '(("one" . 1)
("two" . 2)
("three" . 3)
("four" . 4)
("five" . 5)
("six" . 6)
("seven" . 7)
("eight" . 8)
("nine" . 9)))
(defun digits-to-integer (a b)
(values (parse-integer (format NIL "~A~A" a b))))
(defun line-value (line)
(let* ((first-i (position-if #'digit-char-p line))
(last-i (position-if #'digit-char-p line :from-end T))
(first-val (when first-i (aref line first-i)))
(last-val (when last-i (aref line last-i))))
(loop :for (str . num) :in *numbers*
:for first := (search str line)
:for last := (search str line :from-end T)
:when first
:do (when (or (null first-i)
(< first first-i))
(setf first-i first)
(setf first-val num))
(when (or (null last-i)
(> last last-i))
(setf last-i last)
(setf last-val num)))
(digits-to-integer first-val last-val)))
(defun main ()
(format T
"~A~%"
(loop :for line := (read-line T NIL)
:while line
:unless (string= line "")
:sum (line-value line))))
(eval-when (:execute)
(main))