В одном шаге от счастья

#include <string>
#include <fstream>

using namespace std;

class ticket {
public:
    ticket(int);
    bool test() { return happy; }
private:
    void search();
    int sum(int);
    int prev, current, next;
    bool happy;
};

int main() {
    ifstream ifs;
    ifs.open("INPUT.TXT", ifstream::in);
    if (ifs.is_open()) {
        int size;
        ifs >> size;
        if (size) {
            ofstream ofs;
            ofs.open("OUTPUT.TXT", ifstream::out);
            if (ofs.is_open()) {
                string yes("Yes\n"), no("No\n"), sum("");
                int next;
                for (int n = 0; n < size; n++) {
                    ifs >> next;
                    ticket tick(next);
                    sum += tick.test() ? yes : no;
                }
                ofs << sum;
                ofs.close();
            }
        }
        ifs.close();
    }
    return 0;
}

ticket::ticket(int _ticket) : prev(_ticket - 1), current(_ticket), next(_ticket + 1), happy(false) {
    if (current > 1 && current < 999999) search();
}

void ticket::search() {
    int head = current / 1000, temp = head * 1000, tail = current - temp;
    if (abs(sum(head) - sum(tail)) == 1) {
        head = prev / 1000;
        tail = prev - temp;
        if (sum(head) == sum(tail)) happy = true;
        else {
            head = next / 1000;
            tail = next - temp;
            if (sum(head) == sum(tail)) happy = true;
        }
    }
}

int ticket::sum(int _num) {
    return _num / 100 + _num % 10 + (_num / 10) % 10;
}