Tarjan's Algorithm SCC

/**------------------------
    Author : NikolaP
    Compiler : C++
-------------------------*/

//{         Setup

    #include <bits/stdc++.h>
    using namespace std;

    typedef long long int ll;
    typedef long double ld;
    typedef vector<int> vi;

    const int inf = INT_MAX;
    const bool debug = 0;

//}

struct tarjan{
    int n,time;
    vector<vi> graph;

    tarjan(int _n,int m){
        n = _n;
        time = 0;
        graph.resize(n);

        for(int i = 0 ; i<m ; ++i){
            int from, to;
            cin >> from >> to;
            graph[from].push_back(to);
        }
    }

    void FindComponent(int idx, vi& disc, vi& low, stack<int>& s, vector<bool>& stackitem){
        disc[idx] = low[idx] = ++time;

        s.push(idx);
        stackitem[idx] = true;

        for(int i = 0; i < graph[idx].size(); ++i){
            int to = graph[idx][i];

            if(disc[to] == -1){
                FindComponent(to,disc,low,s,stackitem);
                low[idx] = min(low[idx], low[to]);
            }

            else if(stackitem[to]){
                low[idx] = min(low[idx],disc[to]);
            }

        }

        if(low[idx] == disc[idx]){
            while(s.top() != idx){
                int popped = s.top();

                cout << popped<< " ";
                stackitem[popped] = false;

                s.pop();
            }

            cout << s.top() << '\n';
            stackitem[s.top()] = false;
            s.pop();
        }
    }

    void SCC(){
        vi disc(n,-1),low(n,-1);
        vector<bool> stackitem(n,false);
        stack<int> s;

        for(int i = 0; i < n; ++i){
            if(disc[i] == -1) FindComponent(i,disc,low,s,stackitem);
        }
    }
};

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.precision(8);
    //cout << fixed;

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

    tarjan t = tarjan(n,m);
    t.SCC();

    return 0;
}