###### tags: `Leetcode` `medium` `hash` `python` `Top 100 Liked Questions`

# 49. Group Anagrams

## [題目連結:] https://leetcode.com/problems/group-anagrams/

## 題目:
Given an array of strings ```strs```, group **the anagrams** together. You can return the answer in **any order**.

An **Anagram** is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.

**Example 1:**

Input: strs = ["eat","tea","tan","ate","nat","bat"]
Output: [["bat"],["nat","tan"],["ate","eat","tea"]]

**Example 2:**

Input: strs = [""]
Output: [[""]]

**Example 3:**

Input: strs = ["a"]
Output: [["a"]]

## 解題想法:
* 題目要求輸出相同字符構成的群組
* 解題技巧:
* 用hash table存
* key: 將strs之item按照字母大小排序好
* value: 原strs之item
* 最終return values()即可.

## Python:

from collections import defaultdict
class Solution(object):
    def groupAnagrams(self, strs):
        """
        :type strs: List[str]
        :rtype: List[List[str]]
        """
        map = defaultdict(list)
        for item in strs:
            #list排序: nums.sort()
            #str排序: sorted(str) 排序出來為分開的!!!! 且type為list
            #ex: str='eat'  sorted(str) = ['a','e','t']
            #所以要再合成為單字 作為map的key
            map[''.join(sorted(item))].append(item)
        return map.values()
            
if __name__ == '__main__':
    result = Solution()
    strs = ["eat","tea","tan","ate","nat","bat"]
    ans = result.groupAnagrams(strs)
    print(ans)
        
#Input: strs = ["eat","tea","tan","ate","nat","bat"]
#Output: [["bat"],["nat","tan"],["ate","eat","tea"]]