54. The character stream will not be repeated in the first character (Python)

Title Description

Please implement a function to find the character stream for the first time a character appears only. For example, when the character stream reads only the first two characters "go", the first character only occurs once a "g". When reading out the first six characters "google" from the character stream, first appears only one character is "l".

Output Description:

If the current character stream does not appear there is a character, returns the # character.

 1 class Solution:
 2     # 返回对应char
 3     def __init__(self):
 4         self.stack=[]
 5     def FirstAppearingOnce(self):
 6         # write code here
 7         for e in self.stack:
 8             if self.stack.count(e)==1:
 9                 return e
10         return "#"
11     def Insert(self, char):
12         # write code here
13         self.stack.append(char)

2020-01-01 15:58:47