Create Tarjan's algorithm for finding articulation points.cpp

Author: nikolatechie

Tarjan's algorithm for finding articulation points.cpp

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+#include <bits/stdc++.h>
+#include <ext/rope>
+using namespace std;
+using namespace __gnu_cxx;
+
+using ld = long double;
+using llint = long long;
+using ullint = unsigned long long;
+using pii = pair <int,int>;
+using pcc = pair <char,char>;
+using pss = pair <string,string>;
+using vi = vector <int>;
+using vb = vector <bool>;
+using vii = vi::iterator;
+
+#define INF (1<<30)
+#define MOD 1000000007
+#define mp make_pair
+#define mt make_tuple
+#define all(c) c.begin(), c.end()
+#define ms(name,val) memset(name, val, sizeof name)
+#define np nullptr
+
+
+int n, m;
+vb ap;
+vi disc, low;
+vector <vi> g;
+
+void DFS(int node, int p)
+{
+    static int time = 0;
+    disc[node] = low[node] = ++time;
+    int children = 0;
+
+    for (int &x: g[node])
+    {
+        if (!disc[x])
+        {
+            DFS(x, node);
+            ++children;
+            low[node] = min(low[node], low[x]);
+
+            if (p != -1 && low[x] >= disc[node])
+                ap[node] = 1;
+        }
+        else if (x != p)
+            low[node] = min(low[node], disc[x]);
+    }
+
+    if (p == -1 && children > 1)
+        ap[node] = 1;
+}
+
+int main()
+{
+    ios_base::sync_with_stdio(0);
+    //cin.tie(0);
+
+    cin >> n >> m;
+    g.resize(n);
+    disc.resize(n);
+    low.resize(n);
+    ap.resize(n);
+
+    while (m)
+    {
+        --m;
+        int a, b;
+        cin >> a >> b;
+        g[a].push_back(b);
+        g[b].push_back(a);
+    }
+
+    for (int t1 = 0; t1 < n; ++t1)
+        if (!disc[t1]) DFS(t1, -1);
+
+    for (int t1 = 0; t1 < n; ++t1)
+        if (ap[t1]) cout << t1 << ' ';
+
+    cout << '\n';
+
+
+    return 0;
+}