45 lines
1.5 KiB
EmacsLisp
45 lines
1.5 KiB
EmacsLisp
;;; anagram.el --- Anagram (exercism)
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;;; Commentary:
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;;; Code:
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(provide 'anagram)
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(defun get-char-count (w)
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"Return an associative list of character counts for W."
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(let ((char-list (string-to-list w))
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(char-count ()))
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;; Build an associative list from the character list.
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(dolist (char char-list char-count)
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(let ((entry (assoc char char-count)))
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(if entry (cl-incf (cdr entry))
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(push (cons char 1) char-count))))))
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(defun equal-char-count (char-count comparison-char-count)
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"Return t if the submitted character counts are equal, false otherwise.
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CHAR-COUNT and COMPARISON-CHAR-COUNT should be alists in (character . count) format."
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(let ((are-equal t))
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(dolist (char-count char-count are-equal)
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(if (not are-equal) nil)
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(if (assoc (car char-count) comparison-char-count)
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(if (not (equal
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(cdr char-count)
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(cdr (assoc (car char-count) comparison-char-count))))
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(setq are-equal nil))
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(setq are-equal nil)))))
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(defun anagrams-for (word anagrams)
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"Return all elements of ANAGRAMS which are anagrams for WORD.
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Case insensitive."
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(let ((candidates ())
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(word-char-count (get-char-count (downcase word))))
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(dolist (candidate anagrams candidates)
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(when (and (not (string-equal word candidate))
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(= (length word) (length candidate))
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(equal-char-count word-char-count (get-char-count (downcase candidate))))
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(push candidate candidates)))
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(reverse candidates)))
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;;; anagram.el ends here
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