C++题解 | #字符流中第一个不重复的字符#

class Solution
{
public:
  //Insert one char from stringstream
    queue<char>q; // 队列记录字符次序
    map<char, int>mymap; // map记录字符数量
    void Insert(char ch) {
        mymap[ch] ++;
        if(mymap[ch] == 1) q.push(ch);
    }
  //return the first appearence once char in current stringstream
    char FirstAppearingOnce() {
        char top = q.front();
        while(! q.empty() && mymap[top] != 1){ // 寻找处于队头且数量为1的字符
            q.pop();
            top =q.front();
        }
        return q.empty() ? '#' : top;
    }

};