题解 | #字符流中第一个不重复的字符#

#include <unordered_map>
class Solution
{
public:
    unordered_map<char, int> m;
    string s; // 记录顺序，保证哈希访问顺序
  //Insert one char from stringstream
    void Insert(char ch) {
         s+=ch;
         m[ch]++;
    }
  //return the first appearence once char in current stringstream
    char FirstAppearingOnce() {
        for(int i = 0; i < s.size(); ++i){
            if(m[s[i]] == 1)
            {
                return s[i];
            }
        }
        return '#';
    }

};