LeetCode 49. 字母异位词分组

题目地址：​​https://leetcode-cn.com/problems/group-anagrams/submissions/​​

思路：将每个字符串排序一下，key=排序后的字符， value=原始的字符，放在map中即可

AC代码：

class Solution {

    public List<List<String>> groupAnagrams(String[] strs) {
        Map<String, List<String>> map = new HashMap<>();
        for (int i = 0; i < strs.length; i++) {
            String key = sort(strs[i]);
            List<String> list = map.get(key);
            if (list == null) {
                list = new ArrayList<>();
                list.add(strs[i]);
                map.put(key, list);
            } else {
                list.add(strs[i]);
            }
        }
        List<List<String>> resultList = new ArrayList<>();
        for (List<String> list : map.values()) {
            resultList.add(list);
        }
        return resultList;
    }

    private String sort(String str) {
        char[] charArray = str.toCharArray();
        Arrays.sort(charArray);
        return new String(charArray);
    }
}