Implemented Graph Articulation point checking Algorithm in graph folder

Author: Sanskar-Agrawal01

src/main/java/com/thealgorithms/graph/ArticulationPoint.java

@@ -0,0 +1,70 @@
+package com.thealgorithms.graph;
+import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.List;
+
+public class ArticulationPoint {
+    // Inner class to represent an edge
+    class Edge {
+        int src;
+        int dest;
+
+        public Edge(int s, int d) {
+            this.src = s;
+            this.dest = d;
+        }
+    }
+
+    public static void dfs(ArrayList<Edge>[] graph, int curr, int par, int[] dt, int[] low, boolean[] vis, int time,
+            List<List<Integer>> res) {
+        vis[curr] = true;
+        dt[curr] = low[curr] = ++time;
+        for (int i = 0; i < graph[curr].size(); i++) {
+            Edge e = graph[curr].get(i);
+            int neigh = e.dest;
+            if (neigh == par) {
+                continue;
+            } else if (!vis[neigh]) {
+                dfs(graph, neigh, curr, dt, low, vis, time, res);
+                low[curr] = Math.min(low[neigh], low[curr]);
+                if (dt[curr] < low[neigh]) {
+                    ArrayList<Integer> pair = new ArrayList<>();
+                    pair.add(curr);
+                    pair.add(neigh);
+                    res.add(pair);
+                }
+            } else {
+                low[curr] = Math.min(low[curr], dt[neigh]);
+            }
+        }
+    }
+
+    public static List<List<Integer>> tarjans(ArrayList<Edge>[] graph, int V) {
+        List<List<Integer>> res = new ArrayList<>();
+        int dt[] = new int[V];
+        int low[] = new int[V];
+        int time = 0;
+        boolean vis[] = new boolean[V];
+        for (int i = 0; i < V; i++) {
+            if (!vis[i]) {
+                dfs(graph, i, -1, dt, low, vis, time, res);
+            }
+        }
+        return res;
+    }
+
+    public List<List<Integer>> criticalConnections(int n, List<List<Integer>> connections) {
+        ArrayList<Edge>[] graph = new ArrayList[n];
+        for (int i = 0; i < graph.length; i++) {
+            graph[i] = new ArrayList<>();
+        }
+        for (List<Integer> list : connections) {
+            int u = list.get(0);
+            int v = list.get(1);
+            graph[u].add(new Edge(u, v));
+            graph[v].add(new Edge(v, u));
+        }
+        return tarjans(graph, n);
+    }
+
+}