剑指offer-字符流中第一个不重复的字符-字符串-python

class Solution:
    def __init__(self):
        self.s = ‘‘
        self.queue = []       #按顺序保存所有只出现一次的字符
        self.second = []      #按顺序保存所有出现过的字符
 
    def FirstAppearingOnce(self):
        if self.queue:
            return self.queue[0]
        return ‘#‘
 
    def Insert(self, char):
        self.s += char
        if char in self.queue:
            self.queue.pop(self.queue.index(char))
        elif char not in self.second:
            self.queue.append(char)
            self.second.append(char)