not not kold

@koldinium.com

Certified Grungler he/him koldinium.com

(defun day3-get-maximum-joltage (line number)
(let ((to-remove (- (length line) number))
(stack (make-array number :initial-element 0 :fill-pointer 0 :adjustable t)))
(loop for char across line
for digit = (digit-char-p char)
do (progn
(loop while (and (> to-remove 0) (> (length stack) 0) (> digit (aref stack (1- (length stack)))))
do (progn
(decf to-remove)
(vector-pop stack)))
(vector-push-extend digit stack)))
(loop for i from 0 to (- (length stack) to-remove 1)
sum (* (expt 10 (- number i 1)) (aref stack i)))))

(defun day2-is-invalid-part1 (id)
(let* ((string-repr (format nil "~D" id))
(len (length string-repr))
(half-length (/ len 2)))
(if (not (evenp len))
nil
(string-equal (subseq string-repr 0 half-length)
(subseq string-repr half-length)))))

$(defun day1-part1 () (let ((dial 50)) (with-open-file (stream (asdf:system-relative-pathname "aoc2025" "input/day1.txt") :direction :input) (loop for line = (read-line stream nil 'eof) until (eq line 'eof) sum (let ((dir (if (char= (char line 0) #\L) -1 1)) (mag (parse-integer line :start 1))) (setf dial (mod (+ dial (* dir mag)) 100)) (if (= dial 0) 1 0)))))) (defun day1-part2 () (let ((dial 50)) (with-open-file (stream (asdf:system-relative-pathname "aoc2025" "input/day1.txt") :direction :input) (loop for line = (read-line stream nil 'eof) until (eq line 'eof) sum (let ((dir (if (char= (char line 0) #\L) -1 1)) (mag (parse-integer line :start 1))) (multiple-value-bind (count new-dial) (day1-rotate dial mag dir) (setf dial new-dial) count)))))) (defun day1-rotate (dial mag dir) (let ((count (truncate (+ (mod (* dir dial) 100) mag) 100))) (values count (mod (+ dial (* dir mag)) 100)))) (defun day1 () (format t "PART 1: ~a~%" (day1-part1)) (format t "PART 2: ~a~%" (day1-part2)))$