Elulerian graph algorithm in C++

Author: AMITAERO7

C++/elulerian_graph.cpp

@@ -0,0 +1,150 @@
+#include<iostream> 
+#include <list> 
+using namespace std; 
+  
+
+class Graph 
+{ 
+    int V;    
+    list<int> *adj;    
+public: 
+    // Constructor and destructor 
+    Graph(int V)   {this->V = V; adj = new list<int>[V]; } 
+    ~Graph() { delete [] adj; } 
+  
+    
+    void addEdge(int v, int w); 
+  
+     
+    int isEulerian(); 
+  
+    
+    bool isConnected(); 
+  
+    
+    void DFSUtil(int v, bool visited[]); 
+}; 
+  
+void Graph::addEdge(int v, int w) 
+{ 
+    adj[v].push_back(w); 
+    adj[w].push_back(v);  
+} 
+  
+void Graph::DFSUtil(int v, bool visited[]) 
+{ 
+    
+    visited[v] = true; 
+  
+    
+    list<int>::iterator i; 
+    for (i = adj[v].begin(); i != adj[v].end(); ++i) 
+        if (!visited[*i]) 
+            DFSUtil(*i, visited); 
+} 
+  
+
+bool Graph::isConnected() 
+{ 
+    
+    bool visited[V]; 
+    int i; 
+    for (i = 0; i < V; i++) 
+        visited[i] = false; 
+  
+    
+    for (i = 0; i < V; i++) 
+        if (adj[i].size() != 0) 
+            break; 
+  
+   
+    if (i == V) 
+        return true; 
+  
+   
+    DFSUtil(i, visited); 
+  
+    
+    for (i = 0; i < V; i++) 
+       if (visited[i] == false && adj[i].size() > 0) 
+            return false; 
+  
+    return true; 
+} 
+  
+
+int Graph::isEulerian() 
+{ 
+    
+    if (isConnected() == false) 
+        return 0; 
+  
+   
+    int odd = 0; 
+    for (int i = 0; i < V; i++) 
+        if (adj[i].size() & 1) 
+            odd++; 
+  
+    
+    if (odd > 2) 
+        return 0; 
+  
+    return (odd)? 1 : 2; 
+} 
+  
+
+void test(Graph &g) 
+{ 
+    int res = g.isEulerian(); 
+    if (res == 0) 
+        cout << "graph is not Eulerian\n"; 
+    else if (res == 1) 
+        cout << "graph has a Euler path\n"; 
+    else
+        cout << "graph has a Euler cycle\n"; 
+} 
+  
+
+int main() 
+{ 
+    
+    Graph g1(5); 
+    g1.addEdge(1, 0); 
+    g1.addEdge(0, 2); 
+    g1.addEdge(2, 1); 
+    g1.addEdge(0, 3); 
+    g1.addEdge(3, 4); 
+    test(g1); 
+  
+    Graph g2(5); 
+    g2.addEdge(1, 0); 
+    g2.addEdge(0, 2); 
+    g2.addEdge(2, 1); 
+    g2.addEdge(0, 3); 
+    g2.addEdge(3, 4); 
+    g2.addEdge(4, 0); 
+    test(g2); 
+  
+    Graph g3(5); 
+    g3.addEdge(1, 0); 
+    g3.addEdge(0, 2); 
+    g3.addEdge(2, 1); 
+    g3.addEdge(0, 3); 
+    g3.addEdge(3, 4); 
+    g3.addEdge(1, 3); 
+    test(g3); 
+  
+    
+    Graph g4(3); 
+    g4.addEdge(0, 1); 
+    g4.addEdge(1, 2); 
+    g4.addEdge(2, 0); 
+    test(g4); 
+  
+   
+    Graph g5(3); 
+    test(g5); 
+  
+    return 0; 
+} 
+