Design a data structure for an anagram finder. It should support two operations:

> a. Create the data structure given a list of words. This operation should have complexity O(n log n), where n is the number of words (assuming that words have a bounded length).

Let's define the "key" of a word to be the result of sorting a word.

We compute the key for all words, and store them along with the words. For this, we could use the interface Map.Entry<K,V> from java.util.

We put all the Map.Entry objects into an array (or any ordered data structure).

Then, we sort the array by the keys (i.e., we use the keys for comparing two objects).

The reason to do this is that all anagrams end up next to each other (which will be useful in the next step).

> b. Given a word, find all its anagrams in the data structure. This operation should have complexity O(m + log n), where m is the number of anagrams found for that word and n is the total number of words in the data structure.

Given a word, now you can use binary search (comparing keys again) on the array to find _one_ anagram of it; all other anagrams are adjacent to this one so you can easily get them from here.