布尔变量

#include <bits/stdc++.h>

using namespace std;

long long t,n;

void solve()

{

    string s;

    cin>>s;

    bool ne = 0;//标记变量，用来标记该字符是否重复

    for(long long i = 0;i<s.size();i++){

        ne = 0;

        for(long long j = 0;j<s.size();j++){

            if(s[i] == s[j]&&i != j){

                ne = 1;

            }          

        }

        if(ne == 0){

            cout<<s[i];

            return ;

        }

    }

    cout<<-1;

}