這題就是看奇數點是不是大於2
所以用bool就行了(我真的好省

大概長成這樣

1    bool count_pass[cities]={false};
2    int start,end;
3    for (int i = 0; i < bridges; i++)
4    {
5        cin>>start>>end;
6        count_pass[start] = !count_pass[start];
7        count_pass[end] = !count_pass[end];
8    }