Create 03 - Adjacency List - Hashmap.cpp

Author: JawadSher

23 - Graph Data Structure Problems/01 - Example/03 - Adjacency List - Hashmap.cpp

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+#include <iostream>
+#include <unordered_map>
+#include <list>
+using namespace std;
+
+// Graph Class Definition
+class Graph {
+public:
+    unordered_map<int, list<int>> adjacencyList;  // To store adjacency list
+
+    // Add an edge to the graph
+    void addEdge(int sourceNode, int destinationNode, bool isDirected) {
+        // Add the edge from source to destination
+        adjacencyList[sourceNode].push_back(destinationNode);
+
+        // If the graph is undirected, add the reverse edge
+        if (!isDirected) {
+            adjacencyList[destinationNode].push_back(sourceNode);
+        }
+    }
+
+    // Print the adjacency list of the graph
+    void printGraph() {
+        for (auto vertex : adjacencyList) {
+            cout << vertex.first << " -> ";
+            for (auto neighbor : vertex.second) {
+                cout << neighbor << ", ";
+            }
+            cout << endl;
+        }
+    }
+};
+
+int main() {
+    int numberOfNodes;
+    cout << "Enter the number of nodes in the graph:" << endl;
+    cin >> numberOfNodes;
+
+    int numberOfEdges;
+    cout << "Enter the number of edges in the graph:" << endl;
+    cin >> numberOfEdges;
+
+    Graph graphInstance;  // Create a Graph object
+
+    // Input edges
+    for (int i = 0; i < numberOfEdges; i++) {
+        int sourceNode, destinationNode;
+        cin >> sourceNode >> destinationNode;
+
+        // Add the edge to the graph (default: undirected)
+        graphInstance.addEdge(sourceNode, destinationNode, false);
+    }
+
+    // Print the graph representation
+    graphInstance.printGraph();
+
+    return 0;
+}