Create Articulation Points.cpp

Author: Ashishgup1

Articulation Points.cpp

@@ -0,0 +1,46 @@
+
+const int N = 1e5 + 5;
+
+int n;
+int timer;
+int tin[N], low[N];
+bool vis[N], isArticulation[N];
+vector<int> g[N];
+
+void dfs(int u, int par)
+{
+	vis[u] = 1;
+	tin[u] = low[u] = ++timer;
+	int children = 0;
+	for(auto &it:g[u])
+	{
+		if(it == par)
+			continue;
+		if(vis[it])
+			low[u] = min(low[u], tin[it]);
+		else
+		{
+			dfs(it, u);
+			low[u] = min(low[u], low[it]);
+			if(low[it] >= tin[u] && par != -1)
+				isArticulation[u] = 1;
+			children++;
+		}
+	}
+	if(par == -1 && children > 1)
+		isArticulation[u] = 1;
+}
+
+void articulationPoints()
+{
+	timer = 0;
+	memset(vis, 0, sizeof(vis));
+	memset(isArticulation, 0, sizeof(isArticulation));
+	memset(tin, -1, sizeof(tin));
+	memset(low, -1, sizeof(low));
+	for(int i = 1; i <= n; i++)
+	{
+		if(!vis[i])
+			dfs(i, -1);
+	}
+}