Graph Implementation using Adjency List

#include <iostream>
using namespace std;
// stores adjacency list items
struct adjNode {
	int val, cost;
	adjNode* next;
};
// structure to store edges
struct graphEdge {
	int start_ver, end_ver, weight;
};
class DiaGraph{
	// insert new nodes into adjacency list from given graph
	adjNode* getAdjListNode(int value, int weight, adjNode* head) 	{
		adjNode* newNode = new adjNode;
		newNode->val = value;
		newNode->cost = weight;
		
		newNode->next = head;   // point new node to current head
		return newNode;
	}
	int N;  // number of nodes in the graph
public:
	adjNode **head;                //adjacency list as array of pointers
	// Constructor
	DiaGraph(graphEdge edges[], int n, int N)  {
		// allocate new node
		head = new adjNode*[N]();
		this->N = N;
		// initialize head pointer for all vertices
		for (int i = 0; i < N; ++i)
			head[i] = nullptr;
		// construct directed graph by adding edges to it
		for (unsigned i = 0; i < n; i++)  {
			int start_ver = edges[i].start_ver;
			int end_ver = edges[i].end_ver;
			int weight = edges[i].weight;
			// insert in the beginning
			adjNode* newNode = getAdjListNode(end_ver, weight, head[start_ver]);
			
                        // point head pointer to new node
			head[start_ver] = newNode;
       		 }
	}
      // Destructor
     ~DiaGraph() {
	for (int i = 0; i < N; i++)
 		delete[] head[i];
		delete[] head;
     }
};
// print all adjacent vertices of given vertex
void display_AdjList(adjNode* ptr, int i)
{
	while (ptr != nullptr) {
		cout << "(" << i << ", " << ptr->val
			<< ", " << ptr->cost << ") ";
		ptr = ptr->next;
	}
	cout << endl;
}
// graph implementation
int main()
{
	// graph edges array.
	graphEdge edges[] = {
		// (x, y, w) -> edge from x to y with weight w
		{0,1,2},{0,2,4},{1,4,3},{2,3,2},{3,1,4},{4,3,3}
	};
	int N = 6;      // Number of vertices in the graph
	// calculate number of edges
	int n = sizeof(edges)/sizeof(edges[0]);
	// construct graph
	DiaGraph diagraph(edges, n, N);
	// print adjacency list representation of graph
	cout<<"Graph adjacency list "<<endl<<"(start_vertex, end_vertex, weight):"<<endl;
	for (int i = 0; i < N; i++)
	{
		// display adjacent vertices of vertex i
		display_AdjList(diagraph.head[i], i);
	}
	return 0;
}