Leetcode 389 Find the difference

標籤：gen   pre   class   let   log   轉換   self   return   sel   

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.

本題的解法很類似single number，由於兩個str只有一個字母不同。所以可以用xor。注意使用ord 和 chr 對於char和int之間進行轉換。

 1 class Solution(object): 2     def findTheDifference(self, s, t): 3         """ 4         :type s: str 5         :type t: str 6         :rtype: str 7         """ 8         ans = 0 9         for x in s:10             ans ^= ord(x)11         for y in t:12             ans ^= ord(y)13         return chr(ans)

 

解法二是使用collections.Counter

 1 class Solution(object): 2     def findTheDifference(self, s, t): 3         """ 4         :type s: str 5         :type t: str 6         :rtype: str 7         """ 8         ds = collections.Counter(s) 9         dt = collections.Counter(t)10         return (dt - ds).keys().pop()

 

Leetcode 389 Find the difference