to check whether a graph is connected or not div-bargali#620

to check whether a graph is connected or not

Author: div-bargali

C++/Data-Structures/Graph/ConnectedComponents.cpp

@@ -0,0 +1,77 @@
+
+#include <bits/stdc++.h> 
+using namespace std; 
+#define N 100000 
+
+vector<int> gr1[N], gr2[N]; 
+
+bool vis1[N], vis2[N]; 
+
+// Function to add edges 
+void Add_edge(int u, int v) 
+{ 
+gr1[u].push_back(v); 
+gr2[v].push_back(u); 
+} 
+
+// DFS function 
+void dfs1(int x) 
+{ 
+vis1[x] = true; 
+
+for (auto i : gr1[x]) 
+if (!vis1[i]) 
+dfs1(i); 
+} 
+
+// DFS function 
+void dfs2(int x) 
+{ 
+vis2[x] = true; 
+
+for (auto i : gr2[x]) 
+if (!vis2[i]) 
+dfs2(i); 
+} 
+
+bool Is_Connected(int n) 
+{ 
+// Call for correct direction 
+memset(vis1, false, sizeof vis1); 
+dfs1(1); 
+
+// Call for reverse direction 
+memset(vis2, false, sizeof vis2); 
+dfs2(1); 
+
+for (int i = 1; i <= n; i++) { 
+
+// If any vertex it not visited in any direction 
+// Then graph is not connected 
+if (!vis1[i] and !vis2[i]) 
+return false; 
+} 
+
+// If graph is connected 
+return true; 
+} 
+
+
+int main() 
+{ 
+int n = 4; 
+
+// Add edges 
+Add_edge(1, 2); 
+Add_edge(1, 3); 
+Add_edge(2, 3); 
+Add_edge(3, 4); 
+
+// Function call 
+if (Is_Connected(n)) 
+cout << "Yes"; 
+else
+cout << "No"; 
+
+return 0; 
+}