题目描述

Given an array of strings, group anagrams together.

Example:

Input: [“eat”, “tea”, “tan”, “ate”, “nat”, “bat”],
Output:
[
[“ate”,”eat”,”tea”],
[“nat”,”tan”],
[“bat”]
]
Note:

All inputs will be in lowercase.
The order of your output does not matter.

算法1

时间复杂度 O(nmlog(m))

Java 代码

import java.util.*;

public class Solution {

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

    public List<List<String>> groupAnagrams(String[] strs) {
        int n = strs.length;
        if (n == 0) {
            return res;
        }

        for (String str : strs) {
            char[] strArr = str.toCharArray();
            Arrays.sort(strArr);
            String sortedStr = String.valueOf(strArr);
            if (!map.contains(sortedStr)) {
                map.put(sortedStr, new ArrayList<>());
            }
            map.get(sortedStr).add(str);
        }

        res.addAll(map.values());
        return res;
    }
}