Create Bruteforce Approach.cpp

Author: JawadSher

23 - Graph Data Structure Problems/18 - Articulation Point in Graph/Bruteforce Approach.cpp

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+class Solution {
+public:
+    // Helper function to perform DFS
+    void dfs(int node, vector<int>& visited, vector<vector<int>>& adjacencyList) {
+        visited[node] = true;
+        for (auto neighbour : adjacencyList[node]) {
+            if (!visited[neighbour]) {
+                dfs(neighbour, visited, adjacencyList);
+            }
+        }
+    }
+
+    // Function to find articulation points using brute force
+    vector<int> articulationPoints(int V, vector<int> adj[]) {
+        vector<int> AP; // To store articulation points
+        vector<vector<int>> adjacencyList(V);
+        
+        // Convert adj[] to a vector of vectors
+        for (int i = 0; i < V; i++) {
+            for (auto neighbour : adj[i]) {
+                adjacencyList[i].push_back(neighbour);
+            }
+        }
+        
+        // Check each node as a potential articulation point
+        for (int i = 0; i < V; i++) {
+            vector<int> visited(V, false); // Visited array
+            // Temporarily remove node `i` from the graph
+            vector<vector<int>> tempAdjList = adjacencyList;
+            for (auto& neighbours : tempAdjList) {
+                neighbours.erase(remove(neighbours.begin(), neighbours.end(), i), neighbours.end());
+            }
+            
+            // Perform DFS from a node other than `i`
+            int startNode = (i == 0) ? 1 : 0;
+            dfs(startNode, visited, tempAdjList);
+            
+            // Check if any node is not visited
+            bool isDisconnected = false;
+            for (int j = 0; j < V; j++) {
+                if (j != i && !visited[j]) {
+                    isDisconnected = true;
+                    break;
+                }
+            }
+            
+            // If the graph becomes disconnected, `i` is an articulation point
+            if (isDisconnected) {
+                AP.push_back(i);
+            }
+        }
+        
+        // If no articulation points found, return {-1}
+        if (AP.empty()) {
+            AP.push_back(-1);
+        } else {
+            sort(AP.begin(), AP.end());
+        }
+        
+        return AP;
+    }
+};