Group Anagrams

In [1]:

    

import Data.List


    

In [2]:

    

groupAnagrams :: [String] -> [String]
groupAnagrams xs =
    sortOn sort xs


    

In [3]:

    

groupAnagrams ["hot", "god", "tea", "dog", "eat"]


    

    






["tea","eat","god","dog","hot"]

In [4]:

    

import Test.QuickCheck


    

In [5]:

    

import Data.Function (on)


    

In [6]:

    

import Control.Monad (join)
import Control.Arrow --(***)


    

In [7]:

    

testAnagrams :: [String] -> Bool
testAnagrams xs =
    let
        anagramCompare = (==) `on` sort
        groups = groupBy anagramCompare $ groupAnagrams xs
    in
        anagramCompare (concat groups) xs &&
        let
            heads = map (sort . head) groups
        in
            uncurry (==) $ mapPair length (nub heads, heads)
    where
        mapPair = join (***)


    

In [8]:

    

quickCheck testAnagrams


    

    






+++ OK, passed 100 tests.