graph implementation in c code example

Example 1: graph using djacency matrix c++

// Adjacency Matrix representation in C++

#include <iostream>
using namespace std;

class Graph {
   private:
  bool** adjMatrix;
  int numVertices;

   public:
  // Initialize the matrix to zero
  Graph(int numVertices) {
    this->numVertices = numVertices;
    adjMatrix = new bool*[numVertices];
    for (int i = 0; i < numVertices; i++) {
      adjMatrix[i] = new bool[numVertices];
      for (int j = 0; j < numVertices; j++)
        adjMatrix[i][j] = false;
    }
  }

  // Add edges
  void addEdge(int i, int j) {
    adjMatrix[i][j] = true;
    adjMatrix[j][i] = true;
  }

  // Remove edges
  void removeEdge(int i, int j) {
    adjMatrix[i][j] = false;
    adjMatrix[j][i] = false;
  }

  // Print the martix
  void toString() {
    for (int i = 0; i < numVertices; i++) {
      cout << i << " : ";
      for (int j = 0; j < numVertices; j++)
        cout << adjMatrix[i][j] << " ";
      cout << "\n";
    }
  }

  ~Graph() {
    for (int i = 0; i < numVertices; i++)
      delete[] adjMatrix[i];
    delete[] adjMatrix;
  }
};

int main() {
  Graph g(4);

  g.addEdge(0, 1);
  g.addEdge(0, 2);
  g.addEdge(1, 2);
  g.addEdge(2, 0);
  g.addEdge(2, 3);

  g.toString();
}

Example 2: graph c++

//Code by Soumyadeep Ghosh insta- @soumyadepp
//linked in :  https://www.linkedin.com/in/soumyadeep-ghosh-90a1951b6/
//Basic implementation of undirected graph using OOP

#include <bits/stdc++.h>

using namespace std;

//undirected graph
class graph
{
  vector<int>*adjacency_list; //array of vectors to store adjacency list
  int Vertices;
  public:
    //constructor
    graph(int n)
    {
      Vertices=n;
      adjacency_list=new vector<int>[Vertices]; //dynamic allocation
    }
  
    void add_edge(int,int);
    void display_graph();
};

int main()
{
  graph g1(5);  //graph of 5 vertices indices- 0 to 4
  //adding edges
  g1.add_edge(0,1); //connect node number 0 to node number 1
  g1.add_edge(1,2); //connect node number 1 to node number 2
  g1.add_edge(1,3); //connect node number 1 to node number 3
  g1.add_edge(2,4); //connect node number 2 to node number 4
  g1.add_edge(2,3); //connect node number 2 to node number 3
  //displaying the graph
  cout<<"The entered Graph is "<<endl;
  g1.display_graph();
  return 0;
}

//function definitions
void graph::add_edge( int u,int v )
   {
     if( u >= Vertices || v >= Vertices )
     {
       cout<<"Overflow"<<endl;
       return;
     }
     if( u<0 || v<0 )
     {
       cout<<"underflow"<<endl;
       return;
     }
     adjacency_list[u].push_back(v);
     adjacency_list[v].push_back(u);
   }
  void graph::display_graph()
   {
     for(int i=0;i<Vertices;i++)
     {
       cout<<"Adjacency list of vertex of vertex "<<i<<endl;
       for(auto it:adjacency_list[i]) //traverse through each list
       {
         cout<<it<<" ";
       }
       cout<<endl;
     }
   }
//thank you!