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adamruzicka's solution

to Anagram in the Common Lisp Track

Published at Mar 24 2020 · 0 comments
Test suite

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".


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Inspired by the Extreme Startup game 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.


(ql:quickload "lisp-unit")
#-xlisp-test (load "anagram")

(defpackage #:anagram-test
  (:use #:common-lisp #:lisp-unit))

(in-package #:anagram-test)

(define-test no-matches
  (assert-equal '()
       '("hello" "world" "zombies" "pants"))))

(define-test detect-simple-anagram
  (assert-equal '("tan")
      (anagram:anagrams-for "ant" '("tan" "stand" "at"))))

(define-test does-not-confuse-different-duplicates
  (assert-equal '() (anagram:anagrams-for "galea" '("eagle"))))

(define-test eliminate-anagram-subsets
  (assert-equal '() (anagram:anagrams-for "good" '("dog" "goody"))))

(define-test detect-anagram
  (assert-equal '("inlets")
       '("enlists" "google" "inlets" "banana"))))

(define-test multiple-anagrams
  (assert-equal '("gallery" "regally" "largely")
       '("gallery" "ballerina" "regally" "clergy" "largely" "leading"))))

(define-test case-insensitive-anagrams
  (assert-equal '("Carthorse")
       '("cashregister" "Carthorse" "radishes"))))

(define-test word-is-not-own-anagram
  (assert-equal '()
      (anagram:anagrams-for "banana" '("banana"))))

(define-test word-is-not-own-anagram-case-insensitively
  (assert-equal '()
      (anagram:anagrams-for "bananarama" '("BananaRama"))))

(let ((*print-errors* t)
      (*print-failures* t))
  (run-tests :all :anagram-test))
(in-package #:cl-user)
(defpackage #:anagram
  (:use #:common-lisp)
  (:export #:anagrams-for))

(in-package #:anagram)

(defun letter-counts (word)
  (let ((table (make-hash-table :test 'equalp)))
    (loop for c across word
          do (incf (gethash c table 0)))

(defun anagrams-for (word L)
  (let ((count (letter-counts word)))
    (loop for candidate in L
          when (and (string-not-equal word candidate)
                    (equalp count (letter-counts candidate)))
          collect candidate)))

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