49. Group Anagrams

class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        Map<String,List<String>> map=new HashMap<String, List<String>>();
        for(String str: strs)
        {
            char[] arr=str.toCharArray();
            Arrays.sort(arr);
            String key=new String(arr);
            if(!map.containsKey(key))
                map.put(key, new ArrayList<String>());
            map.get(key).add(str);
        }
        return new ArrayList<List<String>>(map.values());
    }
}