How to sort a text file to find anagrams in O(MN) time complexity where M is the max number of characters and N is the number of words?

Hi I'm new to Python and I want to find groups of anagrams in a file in linear time.Anagrams are basically two or more words which consists of the same alphabet but in different arrangements.

First I read all the words into a list. Apparently, I can use radix sort to sort each word by column and the radix sort should use a stable counting sort. But I don't know exactly what my counting sort should do? Should I write a counting sort function that takes a word and sorts it by alphabetical order? Then call it in radix sort?

Can someone give me a clearer idea on how to approach this problem?Any help will be appreciated thanks!

Hope this helps you. It too is in O(mn)

public List<List<String>> groupAnagrams(String[] strs){
    List<List<String>> result = new ArrayList<List<String>>();
    
    HashMap<ArrayList<Integer>, ArrayList<String>> map = new HashMap<ArrayList<Integer>, HashMap<ArrayList<String>>;
    
    for(String str : strs){
        ArrayList<Integer> arr = new ArrayList<Integer>();
        for(int i=0; i<str.length(); i++){
            arr[str.charAt(i)- 'a']++;
        }
        
        if(map.containsKey(arr)){
            map.get(arr).add(str);
        } else {
            ArrayList<String> al = new ArrayList<String>();
            al.add(str);
            map.put(arr, al);
        }
    }
    
    result.addAll(map.values());
    
    return result;
}