题解 | 找出字符串中第一个只出现一次的字符

#include<bits/stdc++.h>
using namespace std;

int main() {
    string s;
    cin >> s;
    map<char, int> ma;
    for (auto x: s) ma[x]++;
    for (auto x: s)
        if (ma[x] == 1) {
            cout << x << endl;
            return 0;
        }
    cout << -1 << endl;
    return 0;
}