Anagram problem

In this post, I would like to share my solution for an anagram problem. The problems is stated as follows: Write a method to sort an array of strings so that all the anagrams are next to each other.

The problem doesn't state any special conditions (e.g., whether it is necessary to sort the groups of anagrams), so I assume a simple approach. For example, if the input is alert, acre, pool, race, care, loop, alter, later, then the output could be something like acre, race, care, alert, alter, later, pool, loop.

This problem could be solved using hashes. Example is below with the comments.

def anagrams(input)

    hash = Hash.new

    n = 0

    # iterate over the array

    while n < input.length()

        # convert each string into characters and sort

        word = input[n].chars.sort

        # create a new key value if it doesn't exist

        hash[word] ||= []

        # iterate over the remaining words in the array

        (n...input.length).each do |i|

            # compare each word in the remaining array with the first word

            # and add it to hash if it doesn't exist yet

            if word == input[i].chars.sort

                hash[word] << input[i] if !hash[word].include?(input[i])

            end

        end

        n += 1

    end

    # return only values of the hash converted into an array

    hash.values.flatten

end
 
input = ['alert', 'acre', 'pool', 'race', 'care', 'loop', 'alter', 'later']
print anagrams(input)

The output is ["alert", "alter", "later", "acre", "race", "care", "pool", "loop"].

The complexity of this solution seems to be O(n^2) (or very close to it) since we are iterating over each element twice - the outer loop picks an element, and then the inner loop goes over the remaining elements to find all matches; then the process repeats. I would like to think about a better approach in the future.