I found nice solution in Java in the internet, and it worked. However, I really don't understand the question. It says
return all groups of strings that are anagrams.
i.e. if we have two groups of strings that are anagrams we have to return two goups of strings, i.e. we need
List<List<String>>. But in the problem description the method signature is given by
List<String>. Does it mean that we always assume that we have only one group of string every time? Can someone please clarify this for me?
Sorry for the confusion. Please see this link for an explanation.