[uva] 10004 – bicoloring

#include <queue>
#include <vector>
#ifdef LOCAL
#include "stloutput.h"
#endif
#define INF 1000000000

using namespace std;

int () {
    int n, l;
    while (cin >> n, n) {
        vector<vector<int>> v(n);
        cin >> l;
        for (int i = 0; i < l; i++) {
            int a, b;
            cin >> a >> b;
            v[a].push_back(b);
        }

        queue<int> q;
        vector<int> color(n, -1);
        q.push(0);
        color[0] = 0;
        bool check = true;
        while (!q.empty() && check) {
            int tmp = q.front();
            q.pop();
            for (int i = 0; i < v[tmp].size(); i++) {
                if (color[v[tmp][i]] == -1) {
                    q.push(v[tmp][i]);
                    color[v[tmp][i]] = 1 - color[tmp];
                } else if (color[v[tmp][i]] == color[tmp]) {
                    check = false;
                    break;
                }
            }
        }
        check ? cout << "BICOLORABLE." << endl
              : cout << "NOT BICOLORABLE." << endl;
    }
}