Advent of Code 2017 Day 5 solution

adventday5.el

(defun solution-p1 (in)
  (let* ((idx 0)
	 (xs (copy-sequence in))
	 (num-steps 0)
	 (len (length xs)))
    (while (and (> idx -1) (< idx len))
      (let ((cur (aref xs idx)))
	(aset xs idx (+ cur 1))
	(setq idx (+ idx cur))
	(setq num-steps (+ num-steps 1)))
      )
    num-steps)
  )


(defun solution-p2 (in)
  (let* ((idx 0)
	 (xs (copy-sequence in))
	 (num-steps 0)
	 (len (length xs)))
    (while (and (> idx -1) (< idx len))
      (let ((cur (aref xs idx)))
	(if (>= cur 3)
	  (aset xs idx (- cur 1))
	  (aset xs idx (+ cur 1)))
	(setq idx (+ idx cur))
	(setq num-steps (+ num-steps 1)))
      )
    num-steps)
  )