//高频班version
public class Solution {
    /**
     * @param strs: the given array of strings
     * @return: The anagrams which have been divided into groups
     */
    public List<List<String>> groupAnagrams(String[] strs) {
        // write your code here
        Map<String, List<String>> map = new HashMap<>();
        for (String s : strs) {
            char[] sc = s.toCharArray();
            Arrays.sort(sc);
            String key = String.valueOf(sc);
            map.putIfAbsent(key, new ArrayList<>());
            map.get(key).add(s);
        }
        return new ArrayList<>(map.values());
    }
}