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Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 7387c8f97b
commit cb5bb5e222
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23
Task/Run-length-encoding/Common-Lisp/run-length-encoding.lisp Normal file
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(defun group-similar (sequence &key (test 'eql))
(loop for x in (rest sequence)
with temp = (subseq sequence 0 1)
if (funcall test (first temp) x)
do (push x temp)
else
collect temp
and do (setf temp (list x))))
(defun run-length-encode (sequence)
(mapcar (lambda (group) (list (first group) (length group)))
(group-similar (coerce sequence 'list))))
(defun run-length-decode (sequence)
(reduce (lambda (s1 s2) (concatenate 'simple-string s1 s2))
(mapcar (lambda (elem)
(make-string (second elem)
:initial-element
(first elem)))
sequence)))
(run-length-encode "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW")
(run-length-decode '((#\W 12) (#\B 1) (#\W 12) (#\B 3) (#\W 24) (#\B 1)))