49. Group Anagrams

public class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        Map<String, List<String>> map = new HashMap<>();
        
        for(String s : strs)
        {
            char[] key = s.toCharArray();
            Arrays.sort(key);
            String sKey = new String(key);
            List<String> dest = map.get(sKey);
            if(dest == null)
            {
                dest = new ArrayList<String>();
                map.put(sKey, dest);
            }
            dest.add(s);
        }
        
        List<List<String>> ret = new ArrayList<>();
        for(List<String> group: map.values())
        {
            ret.add(group);
        }
        return ret;
    }
}