题目描述

blablabla

样例

class Solution {
public:

    char firstNotRepeatingChar(string s) {
        char res = '#';
        if(!s.size()) return res;
        unordered_map<char, int> mmp; 
        for(int i = 0; i < s.size(); i++) {
            mmp[s[i]] += 1;
        }
        for(int i = 0; i < s.size(); i++){
            if(mmp[s[i]] == 1)
                return s[i];
        }
        return res;

    }
};