21 lines
535 B
Common Lisp
21 lines
535 B
Common Lisp
(defun string-to-list (s)
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(assert (stringp s) (s) "~s :questa non e una stringa")
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(coerce s 'list))
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(defun unique-string (str)
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(concatenate 'string (remove-duplicates (string-to-list str))))
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(defun unique-sequence (str n)
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(if (= (length (unique-string (subseq str 0 n))) n)
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(subseq str 0 n)
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(unique-sequence (subseq str 1) n)))
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(defun part1 (str)
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(+ 4 (search (unique-sequence str 4) str)))
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(let ((in (open "input.txt" :if-does-not-exist nil)))
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(when in
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(print (part1 (read-line in)))
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(close in)))
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