Add elisp/anagram

Work-in-progress.

elisp/anagram/README.md

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+# Anagram
+
+Given a word and a list of possible anagrams, select the correct sublist.
+
+Given `"listen"` and a list of candidates like `"enlists" "google"
+"inlets" "banana"` the program should return a list containing
+`"inlets"`.
+## Source
+
+Inspired by the Extreme Startup game [https://github.com/rchatley/extreme_startup](https://github.com/rchatley/extreme_startup)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

elisp/anagram/anagram-test.el

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+;;; anagram-test.el --- Tests for Anagram (exercism)
+;;; Commentary:
+
+;;; Code:
+
+(load-file "anagram.el")
+
+(ert-deftest no-matches ()
+  (should (equal '() (anagrams-for
+                      "diaper"
+                      '("hello" "world" "zombies" "pants")))))
+
+(ert-deftest detect-simple-anagram ()
+  (should (equal '("tan") (anagrams-for
+                           "ant"
+                           '("tan" "stand" "at")))))
+
+(ert-deftest does-not-confuse-different-duplicates ()
+  (should (equal '() (anagrams-for
+                      "galea"
+                      '("eagle")))))
+
+(ert-deftest eliminate-anagram-subsets ()
+  (should (equal '() (anagrams-for
+                      "good"
+                      '("dog" "goody")))))
+
+(ert-deftest detect-anagram ()
+  (should (equal '("inlets") (anagrams-for
+                              "listen"
+                              '("enlists" "google" "inlets" "banana")))))
+
+(ert-deftest multiple-anagrams ()
+  (should (equal '("gallery" "regally" "largely")
+                 (anagrams-for
+                  "allergy"
+                  '("gallery" "ballerina" "regally" "clergy" "largely" "leading")))))
+
+(ert-deftest case-insensitive-anagrams ()
+    (should (equal '("Carthorse")
+                   (anagrams-for
+                    "Orchestra"
+                    '("cashregister" "Carthorse" "radishes")))))
+
+(ert-deftest word-is-not-own-anagram ()
+  (should (equal '()
+                 (anagrams-for
+                  "banana"
+                  '("banana")))))
+
+
+(provide 'anagram-test)
+;;; anagram-test.el ends here

elisp/anagram/anagram.el

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+;;; anagram.el --- Anagram (exercism)
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'cl)
+
+(provide 'anagram)
+
+(defun make-char-count(s)
+  (let ((char-list (mapcar (lambda (char) (string char)) s))
+        (char-counts ()))
+    ;; Build an associative list from the character list.
+    (dolist (char char-list char-counts)
+      (if (assoc char char-counts)
+          (setcdr (assoc char char-counts)
+                  (1+ (cdr (assoc char char-counts))))
+        (setq char-counts (cons (cons char 1) char-counts))))))
+
+(defun compare-char-counts(char-counts comparison-char-counts)
+  (let ((are-equal t))
+    (dolist (char-count char-counts are-equal)
+      (if (not are-equal) nil)
+      (if (assoc (car char-count) comparison-char-counts)
+          (if (not (equal
+                    (cdr char-count)
+                    (cdr (assoc (car char-count) comparison-char-counts))))
+              (setq are-equal nil))
+        (setq are-equal nil)))))
+
+(defun anagrams-for(word anagrams)
+  (let ((candidates ())
+        (word-char-count (make-char-count word)))
+    (dolist (candidate anagrams candidates)
+      (if (and
+           (not (string-equal word candidate))
+           (equal (length word) (length candidate))
+           (compare-char-counts word-char-count (make-char-count candidate)))
+          (if (> (length candidates) 0)
+              (add-to-list 'candidates candidate t)
+            (setq candidates (cons candidate nil)))))))
+
+;;; anagram.el ends here