Beams_of_arcs_list(oriented)

#define _CRT_SECURE_NO_WARNINGS

#include <iostream>
#include <vector>

using namespace std;

class Graph
{
public:
    const int block = -1;
    int vcount, acount;
    vector<int> I, J, C, H, L;

    Graph(int _vcount, vector<int>& _i, vector<int>& _j) :vcount(_vcount), I(_i), J(_j), acount(_i.size()) {
        C.assign(acount, 0);
        H.assign(vcount, block);
        L.resize(acount);
        MakeList();
    }

    Graph(int _vcount, vector<int>& _i, vector<int>& _j, vector<int>& _c) :vcount(_vcount), I(_i), J(_j), C(_c), acount(_i.size()) {
        H.assign(vcount, block);
        L.resize(acount);
        MakeList();
    }

    void makeList() {
        for (int i(0); i < acount; ++i) {
            int _i(I[i]);
            L[i] = H[_i];
            H[_i] = i;
        }
    }

    void addArc(int i, int j) {
        L[acount] = H[i];
        H[i] = acount;
        acount++;
    }

    void showArcs() {
        cout << "Arcs:" << endl;
        for (int i(0); i < acount; ++i) {
            cout << i + 1 << ": from " << I[i] + 1 << " to " << J[i] + 1 << ", value = " << C[i] << endl;
        }
    }

    void showBeamsOfArcs() {
        cout << "Beams of arcs: " << endl;
        vector <int> ArcsList;
        for (int i(0); i < vcount; ++i) {
            ArcsList.clear();
            for (int k(H[i]); k != -1; ) {
                ArcsList.push_back(k);
                k = L[k];
            }

            int count(ArcsList.size());

            switch (count)
            {
            case 0:
                cout << "From vertex " << i + 1 << " come no arcs";
                break;
            case 1:
                cout << "From vertex " << i + 1 << " comes 1 arc: ";
                break;
            default:
                cout << "From vertex " << i + 1 << " come " << count << " arcs: ";
            }

            if (count > 0) {
                for (int k(0); k < count - 1; ++k) {
                    cout << ArcsList[k] + 1 << ", ";
                }
                cout << ArcsList[count - 1] + 1;
            }

            cout << endl;
        }
    }
};

int main()
{
    freopen("test.txt", "r", stdin);

    int n, m;
    cin >> n >> m;

    vector<int> _i, _j;
    int ii, jj;
    for (int i(0); i < m; ++i) {
        cin >> ii >> jj;
        _i.push_back(ii - 1);
        _j.push_back(jj - 1);
    }

    Graph G(n, _i, _j);


    return 0;
}