Раскраска карты

#define _USE_MATH_DEFINES
#include <iostream>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <vector>
#include <stdio.h>
#include <cmath>
#include <math.h>
#include <queue>
#include <stack>
#include <climits>
#include <deque>
#include <ctime>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int ui;

#define mh() make_heap()
#define poph() pop_heap()
#define pushh() push_heap()
#define sor(n) n.begin(), n.end()
#define mp make_pair

const int maxn = 1000001;
bool used[maxn];
int color[maxn];
vector<int> graf[maxn];

bool bfs(int start)
{
    queue <int>next;
    next.push(start);
    used[start] = 1;
    color[start] = 0;
    bool good = true;
    while (!next.empty())
    {
        int now = next.front();
        next.pop();
        for (int i = 0; i < graf[now].size(); i++)
        {
            if (!used[graf[now][i]])
            {
                used[graf[now][i]] = 1;
                color[graf[now][i]] = !color[now];
                next.push(graf[now][i]);
            }
            else
                if (color[graf[now][i]] == color[now])
                    good = false;
        }
    }
    return good;
}
int main()
{
    ll n;
    ll prom;
    cin >> n;

    for (int i = 1; i <= n; i++)
    {
        cin >> prom;
        while (prom != 0)
        {
            graf[i].push_back(prom);
            graf[prom].push_back(i);
            cin >> prom;
        }
    }
    bool good = true;

    good = bfs(1);
    if (good)
    {
        for (int i = 1; i <= n; i++)
            cout << color[i];
    }
    else
        cout << -1;
    system("pause");
    return 0;
}