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| 1 | +/* |
| 2 | +Refer https://www.geeksforgeeks.org/dijkstras-shortest-path-algorithm-greedy-algo-7/ |
| 3 | +for better understanding |
| 4 | +*/ |
| 5 | +package DataStructures.Graphs; |
| 6 | + |
| 7 | +import java.util.*; |
| 8 | +import java.io.*; |
| 9 | + |
| 10 | +class dijkstras{ |
| 11 | + |
| 12 | + int k=9; |
| 13 | + int minDist(int dist[], Boolean Set[]) |
| 14 | + { |
| 15 | + int min = Integer.MAX_VALUE, min_index = -1; |
| 16 | + |
| 17 | + for (int r = 0; r < k; r++) |
| 18 | + if (Set[r] == false && dist[r] <= min) { |
| 19 | + min = dist[r]; |
| 20 | + min_index = r; |
| 21 | + } |
| 22 | + |
| 23 | + return min_index; |
| 24 | + } |
| 25 | + |
| 26 | + void print(int dist[]) |
| 27 | + { |
| 28 | + System.out.println("Vertex \t\t Distance"); |
| 29 | + for (int i = 0; i < k; i++) |
| 30 | + System.out.println(i + " \t " + dist[i]); |
| 31 | + } |
| 32 | + void dijkstra(int graph[][], int src) |
| 33 | + { |
| 34 | + int dist[] = new int[k]; |
| 35 | + Boolean Set[] = new Boolean[k]; |
| 36 | + |
| 37 | + for (int i = 0; i < k; i++) { |
| 38 | + dist[i] = Integer.MAX_VALUE; |
| 39 | + Set[i] = false; |
| 40 | + } |
| 41 | + |
| 42 | + dist[src] = 0; |
| 43 | + |
| 44 | + for (int c = 0; c < k - 1; c++) { |
| 45 | + |
| 46 | + int u = minDist(dist, Set); |
| 47 | + |
| 48 | + Set[u] = true; |
| 49 | + |
| 50 | + for (int v = 0; v < k; v++) |
| 51 | + |
| 52 | + if (!Set[v] && graph[u][v] != 0 && dist[u] != Integer.MAX_VALUE && dist[u] + graph[u][v] < dist[v]) |
| 53 | + dist[v] = dist[u] + graph[u][v]; |
| 54 | + } |
| 55 | + |
| 56 | + print(dist); |
| 57 | + } |
| 58 | + |
| 59 | + public static void main(String[] args) |
| 60 | + { |
| 61 | + int graph[][] = new int[][] { { 0, 4, 0, 0, 0, 0, 0, 8, 0 }, |
| 62 | + { 4, 0, 8, 0, 0, 0, 0, 11, 0 }, |
| 63 | + { 0, 8, 0, 7, 0, 4, 0, 0, 2 }, |
| 64 | + { 0, 0, 7, 0, 9, 14, 0, 0, 0 }, |
| 65 | + { 0, 0, 0, 9, 0, 10, 0, 0, 0 }, |
| 66 | + { 0, 0, 4, 14, 10, 0, 2, 0, 0 }, |
| 67 | + { 0, 0, 0, 0, 0, 2, 0, 1, 6 }, |
| 68 | + { 8, 11, 0, 0, 0, 0, 1, 0, 7 }, |
| 69 | + { 0, 0, 2, 0, 0, 0, 6, 7, 0 } }; |
| 70 | + dijkstras t = new dijkstras(); |
| 71 | + t.dijkstra(graph, 0); |
| 72 | + }//main |
| 73 | + |
| 74 | +}//djikstras |
| 75 | + |
| 76 | +/* |
| 77 | +OUTPUT : |
| 78 | +Vertex Distance |
| 79 | +0 0 |
| 80 | +1 4 |
| 81 | +2 12 |
| 82 | +3 19 |
| 83 | +4 21 |
| 84 | +5 11 |
| 85 | +6 9 |
| 86 | +7 8 |
| 87 | +8 14 |
| 88 | +*/ |
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