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import java.util.Arrays;
public class Main {
private static final int INF = Integer.MAX_VALUE;
public void dijkstra(int[][] graph, int source, int destination) {
int n = graph.length;
int[] dist = new int[n]; // array to store shortest distances
boolean[] visited = new boolean[n]; // array to mark visited nodes
int[] pred = new int[n]; // array to store predecessors
Arrays.fill(dist, INF); // initialize distances as infinity
dist[source] = 0; // distance from source to source is 0
for (int i = 0; i < n - 1; i++) {
// select the vertex with the minimum distance
int u = minDistance(dist, visited);
visited[u] = true; // mark the vertex as visited
// update distances of adjacent vertices
for (int v = 0; v < n; v++) {
if (!visited[v] && graph[u][v] != 0 && dist[u] != INF && dist[u] + graph[u][v] < dist[v]) {
dist[v] = dist[u] + graph[u][v];
pred[v] = u; // store predecessor
}
}
}
printShortestPath(source, destination, dist, pred); // print the shortest path and distance
}
// helper function to find the vertex with the minimum distance
private int minDistance(int[] dist, boolean[] visited) {
int minDist = INF;
int minVertex = -1;
for (int i = 0; i < dist.length; i++) {
if (!visited[i] && dist[i] < minDist) {
minDist = dist[i];
minVertex = i;
}
}
return minVertex;
}
// helper function to print the shortest path and distance
private void printShortestPath(int source, int destination, int[] dist, int[] pred) {
System.out.print("Shortest path from " + source + " to " + destination + ": ");
if (dist[destination] == INF) {
System.out.println("No path exists.");
return;
}
printPath(pred, destination);
System.out.println("= " + dist[destination]);
}
// helper function to print the path from source to destination vertex
private void printPath(int[] pred, int dest) {
if (pred[dest] != -1) {
printPath(pred, pred[dest]);
System.out.print("-" + dest);
} else {
System.out.print(dest);
}
}
public static void main(String[] args) {
int[][] graph = {
{0, 2, 0, 1, 0},
{2, 0, 4, 3, 0},
{0, 4, 0, 0, 6},
{1, 3, 0, 0, 5},
{0, 0, 6, 5, 0},
};
Main dijkstra = new Main();
dijkstra.dijkstra(graph, 0, 4); // Call dijkstra method with source and destination vertices
}
}
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