给定n个数字，判断哪个数字出现次数是奇数次

# include<iostream>
# include<cstring>
# include<map>
using namespace std;

map<string, bool> hash_map;
int n;

int main()
{
    cin>>n;
    while(n--)
    {
        string str;
        cin>>str;
        if(hash_map.find(str)!=hash_map.end())
            hash_map[str] = !hash_map[str];
        else
            hash_map[str] = false;
    }
    for(auto t:hash_map)
        if(!t.second) cout<<t.first<<endl; 
}