49. Group Anagrams

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:

1 2	Input: strs = ["eat","tea","tan","ate","nat","bat"] Output: [["bat"],["nat","tan"],["ate","eat","tea"]]

Example 2:

1 2	Input: strs = [""] Output: [[""]]

Example 3:

1 2	Input: strs = ["a"] Output: [["a"]]

合併相同字元文字，排序完相同合併。

# T: O(NKlogK), S: O(NK)
# N: length of strs,
# K: maximum length of a string in strs
class Solution(object):
    def groupAnagrams(self, strs):
        ans = collections.defaultdict(list)
        for s in strs:
            ans[tuple(sorted(s))].append(s) # sorted string are equal
        return ans.values()

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