题目描述

blablabla

class Solution{
public:
    //Insert one char from stringstream
    map<char,int> mm;
    int cnt = 1;

    void insert(char ch){
        if(mm[ch] != 0)
            mm[ch] = -1;
        else
            mm[ch] = cnt;
        cnt++;
    }
    //return the first appearence once char in current stringstream
    char firstAppearingOnce(){
        int temp = 1000000;
        char res = '#';
        for(int i = 0; i < 26; i++)
        {
            if(mm['a'+i] != 0 && mm['a'+i] != -1)
                if(temp > mm['a'+i])
                {
                    temp = mm['a'+i];
                    res = 'a'+i;
                }
            if(mm['A'+i] != 0 && mm['A'+i] != -1)
                if(temp > mm['A'+i])
                {
                    temp = mm['A'+i];
                    res = 'A'+i;
                }
        }
        return res;
    }
};