Dijkstras.java

import java.security.Permissions;
import java.util.*;
public class Dijkstras {
static class Edge {

int src;
int dest;
int wt;
public Edge(int s, int d, int w) {
this.src = s;
this.dest = d;
this.wt = w;
}
}
static void createGraph(ArrayList<Edge> graph[]) {
for(int i=0; i<graph.length; i++) {
graph[i] = new ArrayList<>();
}
graph[0].add(new Edge(0, 1, 2));
graph[0].add(new Edge(0, 2, 4));
graph[1].add(new Edge(1, 3, 7));
graph[1].add(new Edge(1, 2, 1));
graph[2].add(new Edge(2, 4, 3));
graph[3].add(new Edge(3, 5, 1));
graph[4].add(new Edge(4, 3, 2));
graph[4].add(new Edge(4, 5, 5));
}
static class Pair implements Comparable<Pair> {
int n;
int path;
public Pair(int n, int path) {
this.n = n;
this.path = path;
}
@Override
public int compareTo(Pair p2) {
return this.path - p2.path;
}
}

public static int[] dijkstra(ArrayList<Edge> graph[], int src) {
PriorityQueue<Pair> pq = new PriorityQueue<>();
int dist[] = new int[graph.length];
boolean vis[] = new boolean[graph.length];
for(int i=0; i<dist.length; i++) {
if(i != src) {
dist[i] = Integer.MAX_VALUE;
}
}
pq.add(new Pair(src, 0));
while(!pq.isEmpty()) {
Pair curr = pq.remove();
if(!vis[curr.n]) {
vis[curr.n] = true;
for(int i=0; i<graph[curr.n].size(); i++) {
Edge e = graph[curr.n].get(i);
int u = e.src;
int v = e.dest;
if(!vis[v] && dist[u]+e.wt < dist[v]) {
dist[v] = dist[u] + e.wt;
pq.add(new Pair(v, dist[v]));
}
}
}
}
return dist;
}
public static void main(String args[]) {
int V = 6;
ArrayList<Edge> graph[] = new ArrayList[V];
createGraph(graph);
int src = 0;
int dist[] = dijkstra(graph, src);
for(int i=0; i<dist.length; i++) {
System.out.print(dist[i]+" ");
}

}
}