Dijkstra_algorithm.cpp

#include <bits/stdc++.h>
using namespace std;
#define INF 0x3f3f3f3f

typedef pair<int, int> iPair;

class Graph 
{
	int V; 
	list<pair<int, int> >* adj;

public:
	Graph(int V); 
	void addEdge(int u, int v, int w);
	void shortestPath(int s);
};

Graph::Graph(int V)
{
	this->V = V;
	adj = new list<iPair>[V];
}

void Graph::addEdge(int u, int v, int w)
{
	adj[u].push_back(make_pair(v, w));
	adj[v].push_back(make_pair(u, w));
}

void Graph::shortestPath(int src)
{
	
	priority_queue<iPair, vector<iPair>, greater<iPair> >
		pq;

	vector<int> dist(V, INF);

	pq.push(make_pair(0, src));
	dist[src] = 0;

	while (!pq.empty()) 
	{
		
		int u = pq.top().second;
		pq.pop();

	
		list<pair<int, int> >::iterator i;
		for (i = adj[u].begin(); i != adj[u].end(); ++i)
		{
			
			int v = (*i).first;
			int weight = (*i).second;

			if (dist[v] > dist[u] + weight) {
				dist[v] = dist[u] + weight;
				pq.push(make_pair(dist[v], v));
			}
		}
	}

	printf("Vertex Distance from Source\n");
	for (int i = 0; i < V; ++i)
		printf("%d \t\t %d\n", i, dist[i]);
}

int main()
{
	int V = 9;
	Graph g(V);
	clock_t t=clock();

	g.addEdge(0, 1, 4);
	g.addEdge(0, 7, 8);
	g.addEdge(1, 2, 8);
	g.addEdge(1, 7, 11);
	g.addEdge(2, 3, 7);
	g.addEdge(2, 8, 2);
	g.addEdge(2, 5, 4);
	g.addEdge(3, 4, 9);
	g.addEdge(3, 5, 14);
	g.addEdge(4, 5, 10);
	g.addEdge(5, 6, 2);
	g.addEdge(6, 7, 1);
	g.addEdge(6, 8, 6);
	g.addEdge(7, 8, 7);

	// Function call
	g.shortestPath(0);
	double time_taken=((double)t/CLOCKS_PER_SEC);
	cout<<endl<<time_taken<<endl;
	return 0;
}