> For the complete documentation index, see [llms.txt](https://mayanktyagi3111.gitbook.io/interview-prep/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mayanktyagi3111.gitbook.io/interview-prep/hashmap-and-hashset-and-sliding-window/group-anagrams.md).

# Group Anagrams

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.

```java
class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        if (strs == null || strs.length == 0)
            return new ArrayList<>();
        Map<String, List<String>> map = new HashMap<>();
        for (String s : strs) {
            char[] arr = new char[26];
            for (char c : s.toCharArray())
                arr[c - 'a']++;
            String key = new String(arr);
            map.computeIfAbsent(key, k -> new ArrayList<>()).add(s);
        }
        return new ArrayList<>(map.values());
    }
}
```