50扩展. 字符流中第一个只出现一次的字符

# -*- coding:utf-8 -*-
class Solution:
    # 返回对应char
    def __init__(self):
        self.sdict = {}
        self.slist = []
    def FirstAppearingOnce(self):
        # write code here
        if not self.slist:
            return '#'
        for i in self.slist:
            if self.sdict[i] == 1:
                return i
        return '#'
    def Insert(self, char):
        # write code here
        self.slist.append(char)
        for i in char:
            if i in self.sdict:
                self.sdict[i] += 1
            else:
                self.sdict[i] = 1