题解 | #第一个只出现一次的字符#

class Solution {
public:
    int FirstNotRepeatingChar(string str) {
        unordered_map<char,int> map;
        for (auto s : str)
            map[s]++;
        for (int i = 0; i < str.size(); i++){
            if (map[str[i]] == 1)
                return i;
        }
        return -1;
    }
};