字母异位词分组

哈希思想

public List<List<String>> groupAnagrams(String[] strs){

Map<String,List<String>> map = new HashMap();

for(String str : strs){

char[] array = str.toCharArray();

Arrays.sort(array);

String key = new String(array);

List<String> list = map.getOrDefault(key,new ArrayList<String>());

list.add(str);

map.put(key,list);

}

return new ArrayList<List<String>>(map.values());

}