anagram.hs

import List
import qualified Data.Map as Map

-- Given as stdin
-- presents
-- serpents
-- no
-- on
-- whatever
-- Expected Output:
-- [["serpents","presents"],["on","no"]]

-- This version only displays words that have more than one 
-- match in the list, and sorts by the words that got the most matches.

-- Can we do the map bit better?

main = do
  input <- getContents
  print $ anagrams $ lines input

anagrams words = 
  sorted_anagrams
  where 
    sorted_anagrams = sortBy sorter filtered_anagrams
    sorter a b = compare (length b)  (length a)
    filtered_anagrams = Map.elems $ Map.filter filter_function all_anagrams
    filter_function words = length words > 1
    all_anagrams = do_anagrams words Map.empty
    do_anagrams [] result = result  
    do_anagrams words result = do_anagrams 
                                 (tail words) 
                                 (Map.unionWith 
                                   (++) 
                                   (Map.fromList [(sorted_current_word, [current_word])])
                                   result)
      where 
        current_word = head words
        sorted_current_word = sort current_word

anagram.rb

input = STDIN.read.split("\n")
 
result = Hash.new([])
 
input.each do |word|
  sorted_word = word.split('').sort.join
  result[sorted_word] += [word]
end
 
values = result.values.sort { |a, b| b.size <=> a.size }
 
p values[0..3]