Given an array of strings, group anagrams together.

For example, given: ["eat", "tea", "tan", "ate", "nat", "bat"],
Return:

[
["ate", "eat","tea"],
["nat","tan"],
["bat"]
]

大意就是找出相同字符组成的所有的字符串

  public List<List<String>> groupAnagrams(String[] strs) {
        List<List<String>> result = new ArrayList<List<String>>();
        if(strs == null || strs.length == 0){
            return result;
        }

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

        /**
         * 利用Arrays.sort的能力将相同char组成的不同String筛选出来
         */
        for(String str : strs){
            char[] chars = str.toCharArray();
            Arrays.sort(chars);
            String tmp = String.valueOf(chars);
            if(map.containsKey(tmp)){
                map.get(tmp).add(str);
            }else{
                List<String> list = new ArrayList<String>();
                list.add(str);
                map.put(tmp, list);
            }
        }
        result.addAll(map.values());
        return result;
    }