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Dijkastra.java
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Dijkastra.java
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import java.util.*;
class Dijkstra {
private static final int V = 9; // Number of vertices in the graph
// A utility function to find the vertex with minimum distance value
int minDistance(int dist[], boolean sptSet[]) {
int min = Integer.MAX_VALUE, min_index = -1;
for (int v = 0; v < V; v++)
if (!sptSet[v] && dist[v] <= min) {
min = dist[v];
min_index = v;
}
return min_index;
}
// Function that implements Dijkstra's single source shortest path algorithm
void dijkstra(int graph[][], int src) {
int dist[] = new int[V]; // The output array. dist[i] will hold the shortest distance from src to i
boolean sptSet[] = new boolean[V]; // sptSet[i] will be true if vertex i is included in shortest path tree
// Initialize all distances as INFINITE and stpSet[] as false
for (int i = 0; i < V; i++) {
dist[i] = Integer.MAX_VALUE;
sptSet[i] = false;
}
// Distance of source vertex from itself is always 0
dist[src] = 0;
// Find shortest path for all vertices
for (int count = 0; count < V - 1; count++) {
// Pick the minimum distance vertex from the set of vertices not yet processed
int u = minDistance(dist, sptSet);
// Mark the picked vertex as processed
sptSet[u] = true;
// Update dist value of the adjacent vertices of the picked vertex
for (int v = 0; v < V; v++)
if (!sptSet[v] && graph[u][v] != 0 && dist[u] != Integer.MAX_VALUE && dist[u] + graph[u][v] < dist[v])
dist[v] = dist[u] + graph[u][v];
}
// Print the constructed distance array
printSolution(dist);
}
// A utility function to print the constructed distance array
void printSolution(int dist[]) {
System.out.println("Vertex \t Distance from Source");
for (int i = 0; i < V; i++)
System.out.println(i + " \t\t " + dist[i]);
}
public static void main(String[] args) {
int graph[][] = new int[][] { { 0, 4, 0, 0, 0, 0, 0, 8, 0 },
{ 4, 0, 8, 0, 0, 0, 0, 11, 0 },
{ 0, 8, 0, 7, 0, 4, 0, 0, 2 },
{ 0, 0, 7, 0, 9, 14, 0, 0, 0 },
{ 0, 0, 0, 9, 0, 10, 0, 0, 0 },
{ 0, 0, 4, 14, 10, 0, 2, 0, 0 },
{ 0, 0, 0, 0, 0, 2, 0, 1, 6 },
{ 8, 11, 0, 0, 0, 0, 1, 0, 7 },
{ 0, 0, 2, 0, 0, 0, 6, 7, 0 } };
Dijkstra t = new Dijkstra();
t.dijkstra(graph, 0);
}
}