Created
April 19, 2020 13:39
-
-
Save myrtleTree33/260e1b983bc7f1363fb38896bfbff585 to your computer and use it in GitHub Desktop.
Dijkstra's shortest distance in Java
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
import java.util.HashSet; | |
import java.util.Set; | |
public class Djistrika { | |
public static final int V = 9; | |
public static void dijkstra(int[][] graph, int ref) { | |
// Initialize vars | |
final int VV = graph.length; | |
Set<Integer> explored = new HashSet<>(); | |
int[] dist = new int[VV]; | |
// Initialize dist array | |
// Always set source to 0 (dist[0] = 0) | |
for (int i = 1; i < VV; i++) { | |
dist[i] = Integer.MAX_VALUE; | |
} | |
// At most, we iterate across all vertices. | |
for (int i = 0; i < VV - 1; i++) { | |
int node = chooseNextNode(dist, explored); | |
explored.add(node); | |
for (int j = 0; j < VV; j++) { | |
if (!explored.contains(j) | |
&& graph[i][j] != 0 // in set | |
&& dist[i] != Integer.MAX_VALUE // there is path from 0 to i previously | |
&& dist[i] + graph[i][j] < dist[j] // there is a path from i to j, and lesser than dist from 0 to j | |
) { | |
dist[j] = dist[i] + graph[i][j]; | |
} | |
} | |
} | |
printDists(dist); | |
} | |
private static int chooseNextNode(int[] dists, Set<Integer> explored) { | |
int min = Integer.MAX_VALUE; | |
int node = -1; | |
for (int i = 0; i < dists.length; i++) { | |
if (!explored.contains(i) && dists[i] < min) { | |
node = i; | |
} | |
} | |
return node; | |
} | |
private static void printDists(int[] dist) { | |
for (int i = 0; i < dist.length; i++) { | |
System.out.println(String.format("Ref=%d Dist=%d", i, dist[i])); | |
} | |
} | |
public static void main(String[] arg) { | |
int graph[][] = {{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(graph, 0); | |
} | |
} | |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment