(Java)LeetCode-49. Group Anagrams

Given an array of strings, group anagrams together.

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

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

Note: All inputs will be in lower-case

這一題我是這麼想的，將每個字符串排好序後，作爲Hashmap的Key，排序之前的字符串作爲value，最後將所有的value放入一個List裏即可

代碼如下：

public List<List<String>> groupAnagrams(String[] strs) {
		Map<String,List<String>> map = new HashMap<String, List<String>>();
		for(String str : strs){
			char[] ch = str.toCharArray();
			Arrays.sort(ch);
			String temp = (new String(ch));
			if(map.containsKey(temp)){
				map.get(temp).add(str);
			}else{
				List<String> list = new ArrayList<String>();
				list.add(str);
				map.put(temp, list);
			}
		}
		Iterator<Map.Entry<String, List<String>>> iter = map.entrySet().iterator();
		List<List<String>> result = new ArrayList<List<String>>();
		while(iter.hasNext()){
			Map.Entry<String, List<String>> entry = (Map.Entry<String, List<String>>)iter.next();
	//		System.out.println(entry.getValue());
			result.add(entry.getValue());
		}
		return result;
    }

不過我在discuss裏看到一種超快的解法，很巧妙，連接是https://discuss.leetcode.com/topic/45639/java-beat-100-use-prime-number