DijkstraAlgo.java

import java.util.*;
public class Solution {
	
	public static ArrayList < Integer > dijkstra(ArrayList< ArrayList < Integer > > vec, int vertices, int edges, int source){
        //To Store the result
		ArrayList<Integer> result = new ArrayList<>();
        for(int i=0;i<vertices;i++){
            result.add(Integer.MAX_VALUE);
        }
        
        //Adjacency List
        ArrayList<ArrayList<Node>> adjList = new ArrayList<>();
        for(int i=0;i<vertices;i++){
            adjList.add(new ArrayList<Node>());
        }
        result.set(0,0);
        for(ArrayList<Integer> ve : vec){
            adjList.get(ve.get(0)).add(new Node(ve.get(1),ve.get(2)));
            adjList.get(ve.get(1)).add(new Node(ve.get(0),ve.get(2)));
        }
        
        //Priority Queue to keep track of min cost
        PriorityQueue<Node> queue = new PriorityQueue<Node>(vertices,new Node());
        queue.offer(new Node(0,0));
        
        while(!queue.isEmpty()){
            Node temp = queue.poll();
            for(Node x : adjList.get(temp.v)){
                if(result.get(temp.v) + x.cost< result.get(x.v)){
                    result.set(x.v,(result.get(temp.v) + x.cost));
                    queue.offer(new Node(x.v,result.get(x.v)));
                }
            }
        }
        
        return result;
	}
}
class Node implements Comparator<Node>{
    int v;
    int cost;
    Node(){}
    Node(int _v,int _cost){
        v = _v;
        cost = _cost;
    }
    @Override
    public int compare(Node a,Node b){
        return a.cost-b.cost;
    }
}