https://adventofcode.com/2017/day/10

day_10.el

;;; -*- lexical-binding: t -*-

(defun dowrap (list beg_i l lambd)
  (let (i)
    (dotimes (j l)
      (setq i (+ beg_i j))
      (setq i (% i (length list)))
      (apply lambd (list i j))
      )
    )
  )

(dowrap '(1 2 3 4) 2 2 (lambda (i j) (print (format "i %d j %d" i j)))
        )

(defun sublist-wrap (list beg_i l)
  (let (res)
    (dowrap
     list
     beg_i
     l
     (lambda (i j)
       (push (nth i list) res)
       )
     )
    res
    )
  )

(defun reverse-wrap-list (list beg_i l)
  (let ((rev-sub (sublist-wrap list beg_i l)))
   (dowrap
    list
    beg_i
    l
    (lambda (i j)
      (setf (nth i list) (nth j rev-sub))
      )
    )
   )
  list
  )


(sublist-wrap '(1 2 3 4) 2 3) ;; 1 4 3
(sublist-wrap '(1 2 3 4) 0 2) ;; 2 1
(sublist-wrap '(0 1 2 3) 0 3)

(reverse-wrap-list '(1 2 3 4 5) 0 3) ;; 3 2 1 4 5
(reverse-wrap-list '(1 2 3 4 5 6) 4 4) ;; 6 5 3 4 2 1

(defun knot-hash-round (list input i off)
  (let ()
    (dolist (el input)
      (reverse-wrap-list list i el)
      (setq i (+ i (+ el off)))
      (setq i (% i (length list)))
      (setq off (1+ off))
      )
    (print (format "Part 1: %d" (* (nth 0 list) (nth 1 list))))
    (list i off)
    )
  )

(knot-hash-round '(0 1 2 3 4) '(3 4 1 5) 0 0) ;; 12

(defun generate-input ()
  (let (res)
    (dotimes (i 256 (reverse res))
      (push i res)
      )
    )
  )

(defun to-hex (n)
  (substring (format "0%x" n) -2)
  )

(defun knot-hash (input)
  (let (round_res (rounds 64) (list (generate-input)) (input (append input '(17 31 73 47 23))) (i 0) (off 0))
    (dotimes (_ rounds)
      (setq round_res (knot-hash-round list input i off))
      (setq i (nth 0 round_res))
      (setq off (nth 1 round_res))
      )
    (let (res (acc 0) val)
      (dotimes (i (length list) (string-join (reverse res) ""))
        (setq val (nth i list))
        (setq acc (logxor acc val))
        (when (= (% (1+ i) 16) 0) (progn
                                    (push (to-hex acc) res)
                                    (setq acc 0)
                                  )
          )
        )
      )
    )
  )

(knot-hash (convert-to-ascii "192,69,168,160,78,1,166,28,0,83,198,2,254,255,41,12"))

(knot-hash-round (generate-input) '(192 69 168 160 78 1 166 28 0 83 198 2 254 255 41 12) 0 0)

(defun convert-to-ascii (str)
    (mapcar (lambda (ch) (aref ch 0)) (split-string str "" t))
  )

(knot-hash (convert-to-ascii "")) ;; a2582a3a0e66e6e86e3812dcb672a272
(knot-hash (convert-to-ascii "AoC 2017")) ;; 33efeb34ea91902bb2f59c9920caa6cd
(knot-hash (convert-to-ascii "1,2,3")) ;; 3efbe78a8d82f29979031a4aa0b16a9d
(knot-hash (convert-to-ascii "1,2,4")) ;; 63960835bcdc130f0b66d7ff4f6a5a8e