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Given two strings s and t which consist of only lowercase letters.

String t is generated by random shuffling string s and then add one more letter at a random position.

Find the letter that was added in t.

Example:

Input:s = "abcd"t = "abcde"Output:eExplanation:'e' is the letter that was added.

思路：比较两个字符串中新添加的字符（字符顺序可能不同）。最开始想法是利用两个字符串的Counters直接相减，返回不同：

from collections import Counterclass Solution:    def findTheDifference(self, s, t):        """        :type s: str        :type t: str        :rtype: str        """        dic1 = Counter(s)        dic2 = Counter(t)                return(list(dic2-dic1)[0])

又想到两个字符串除了一个字符不同，剩下全都一致，那么两个字符串加起来，只有这一个多添加的字符个数为奇数。方法有很多。

from collections import Counterclass Solution:    def findTheDifference(self, s, t):        """        :type s: str        :type t: str        :rtype: str        """        dic = Counter(s+t)        for k,v in dic.items():            if v%2 !=0 :                return k

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