# [Group Anagrams][title]

## Description

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.

**Tags:** Hash Table, String


## 思路

题意是给你一组字符串，让你把其中同位异构字符串分组，同位异构字符串就是组成字符串的字符都相同，但是字符放的位置可以不同。既然要分组，那么关键就是如何确定他们是同位异构字符串呢，想到的自然就是对其排序，排序之后他们就都是同一个字符串了，就可以归为一类了，代码如下所示。

```java
class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        if (strs == null || strs.length == 0) return Collections.emptyList();
        List<List<String>> list = new ArrayList<>();
        Map<String, Integer> hash = new HashMap<>();
        int i = 0;
        for (String str : strs) {
            char[] c = str.toCharArray();
            Arrays.sort(c);
            String sortStr = String.valueOf(c);
            if (!hash.containsKey(sortStr)) {
                hash.put(sortStr, i++);
                List<String> sub = new ArrayList<>();
                sub.add(str);
                list.add(sub);
            } else {
                list.get(hash.get(sortStr)).add(str);
            }
        }
        return list;
    }
}
```


## 结语

如果你同我一样热爱数据结构、算法、LeetCode，可以关注我 GitHub 上的 LeetCode 题解：[awesome-java-leetcode][ajl]



[title]: https://leetcode.com/problems/group-anagrams
[ajl]: https://github.com/Blankj/awesome-java-leetcode