Group Anagrams

题目
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.

答案

class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        List<List<String>> list = new ArrayList<List<String>>();
        HashMap<String, List<String>> map = new HashMap<String, List<String>>();
        
        for(int i = 0; i < strs.length; i++) {
            char[] curr_chrs = strs[i].toCharArray();
            Arrays.sort(curr_chrs);
            String curr_str = String.valueOf(curr_chrs);
            List<String> l = map.get(curr_str);
            if(l == null) {
                l = new ArrayList<String>();
                list.add(l);
                map.put(curr_str, l);
            }
            l.add(strs[i]);
        }
        return list;
    }
}