Ap.c++
====

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <set>

using namespace std;

vector<vector<int>> adj;
vector<int> DFN, Low, parent;
vector<bool> visited;
int timer = 0;
set<int> articulation_points;

void DFS(int u) {
    visited[u] = true;
    DFN[u] = Low[u] = timer++;
    int children = 0;

    for (int v : adj[u]) {
        if (!visited[v]) {
            children++;
            parent[v] = u;
            DFS(v);
            Low[u] = min(Low[u], Low[v]);

            if (parent[u] == -1 && children > 1)
                articulation_points.insert(u);

            if (parent[u] != -1 && Low[v] >= DFN[u])
                articulation_points.insert(u);
        }
        else if (v != parent[u]) {
            Low[u] = min(Low[u], DFN[v]);
        }
    }
}

int main() {
    ifstream file("AP.txt");
    if (!file) {
        cerr << "Unable to open file AP.txt";
        exit(1);
    }

    int n;
    file >> n;

    vector<int> values(n);
    vector<int> index(n);
    vector<int> search_order(10);

    for (int i = 0; i < n; i++)
        file >> index[i];

    for (int i = 0; i < n; i++)
        file >> values[i];

    for (int i = 0; i < values[0]-1; i++)
        file >> search_order[i];

    adj.resize(values[0]-1);
    DFN.resize(values[0]-1, -1);
    Low.resize(values[0]-1, -1);
    parent.resize(values[0]-1, -1);
    visited.resize(values[0]-1, false);

    for (int i = 0; i < values[0]-1; i++) {
        int start = values[i];
        int end = values[i+1];
        for (int j = start; j < end; j++) {
            adj[i].push_back(values[j]);
            adj[values[j]].push_back(i);
        }
    }

    for (int i = 0; i < values[0]-1; i++) {
        if (!visited[search_order[i]])
            DFS(search_order[i]);
    }

    for (int i = 0; i < values[0]-1; i++) {
        cout << "Node " << i << ": DFN = " << DFN[i] << ", Low = " << Low[i] << endl;
    }

    cout << "Articulation points: ";
    for (int point : articulation_points) {
        cout << point << " ";
    }
    cout << endl;

    return 0;
}