49. 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"]
]

https://leetcode.wang/leetCode-49-Group-Anagrams.html

Solution1

Time O(NKlogK) N is # of string , K is max length
Space O(NK) store in res
注意问题：
python :

• sorted(list)返回new list
• list.sort() 直接对list进行modifiy 返回NONE
• dict 的 key should be immutable

class Solution(object):
    def groupAnagrams(self, strs):
        """
        :type strs: List[str]
        :rtype: List[List[str]]
        """
        res = {}
        
        for s in strs:
            key = tuple(sorted(s))
            if res.has_key():
                res[key].append(s)
            else:
                res[key] = [s]
        return res.values()

Solution2

新建一个【0，0，0... 】26*1的listcount出钱频次
然后以他为key建dict

class Solution(object):
    def groupAnagrams(self, strs):
        """
        :type strs: List[str]
        :rtype: List[List[str]]
        """
        res = {}
       
        for s in strs:
            a = [0]*26
            for c in s:
                a[ord(c)-ord('a')] +=1
            
            key = tuple(a)
            if res.has_key(key):
                res[key].append(s)
            else:
                res[key] = [s]
        return res.values()