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Dijkstra’s Algorithm – Shortest distance
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Dijkstra’s Algorithm – Shortest distance
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import java.util.*;
class Node implements Comparator<Node>
{
private int v;
private int weight;
Node(int _v, int _w) { v = _v; weight = _w; }
Node() {}
int getV() { return v; }
int getWeight() { return weight; }
@Override
public int compare(Node node1, Node node2)
{
if (node1.weight < node2.weight)
return -1;
if (node1.weight > node2.weight)
return 1;
return 0;
}
}
class Main
{
void shortestPath(int s, ArrayList<ArrayList<Node>> adj, int N)
{
int dist[] = new int[N];
for(int i = 0;i<N;i++) dist[i] = 100000000;
dist[s] = 0;
PriorityQueue<Node> pq = new PriorityQueue<Node>(N, new Node());
pq.add(new Node(s, 0));
while(pq.size() > 0) {
Node node = pq.poll();
for(Node it: adj.get(node.getV())) {
if(dist[node.getV()] + it.getWeight() < dist[it.getV()]) {
dist[it.getV()] = dist[node.getV()] + it.getWeight();
pq.add(new Node(it.getV(), dist[it.getV()]));
}
}
}
System.out.println("The distances from source "+s+" are : ");
for (int i = 0; i < N; i++)
{
System.out.print( dist[i] + " ");
}
}
public static void main(String args[])
{
int n = 5;
ArrayList<ArrayList<Node> > adj = new ArrayList<ArrayList<Node> >();
for (int i = 0; i < n; i++)
adj.add(new ArrayList<Node>());
adj.get(0).add(new Node(1, 2));
adj.get(1).add(new Node(0, 2));
adj.get(1).add(new Node(2, 4));
adj.get(2).add(new Node(1, 4));
adj.get(0).add(new Node(3, 1));
adj.get(3).add(new Node(0, 1));
adj.get(3).add(new Node(2, 3));
adj.get(2).add(new Node(3, 3));
adj.get(1).add(new Node(4, 5));
adj.get(4).add(new Node(1, 5));
adj.get(2).add(new Node(4, 1));
adj.get(4).add(new Node(2, 1));
Main obj = new Main();
obj.shortestPath(0, adj, n);
}
}