Merge pull request #44 from asr0104/patch-1

Create dijkstra.c++

graph/dijkstra.c++

@@ -0,0 +1,89 @@
+#include <stdio.h> 
+#include <limits.h> 
+
+// Number of vertices in the graph 
+#define V 9 
+
+// A utility function to find the vertex with minimum distance value, from 
+// the set of vertices not yet included in shortest path tree 
+int minDistance(int dist[], bool sptSet[]) 
+{ 
+   // Initialize min value 
+   int min = INT_MAX, min_index; 
+
+   for (int v = 0; v < V; v++) 
+     if (sptSet[v] == false && dist[v] <= min) 
+         min = dist[v], min_index = v; 
+
+   return min_index; 
+} 
+
+// A utility function to print the constructed distance array 
+int printSolution(int dist[], int n) 
+{ 
+   printf("Vertex   Distance from Source\n"); 
+   for (int i = 0; i < V; i++) 
+      printf("%d tt %d\n", i, dist[i]); 
+} 
+
+// Function that implements Dijkstra's single source shortest path algorithm 
+// for a graph represented using adjacency matrix representation 
+void dijkstra(int graph[V][V], int src) 
+{ 
+     int dist[V];     // The output array.  dist[i] will hold the shortest 
+                      // distance from src to i 
+
+     bool sptSet[V]; // sptSet[i] will true if vertex i is included in shortest 
+                     // path tree or shortest distance from src to i is finalized 
+
+     // Initialize all distances as INFINITE and stpSet[] as false 
+     for (int i = 0; i < V; i++) 
+        dist[i] = INT_MAX, 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. u is always equal to src in the first iteration. 
+       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++) 
+
+         // Update dist[v] only if is not in sptSet, there is an edge from  
+         // u to v, and total weight of path from src to  v through u is  
+         // smaller than current value of dist[v] 
+         if (!sptSet[v] && graph[u][v] && dist[u] != INT_MAX  
+                                       && dist[u]+graph[u][v] < dist[v]) 
+            dist[v] = dist[u] + graph[u][v]; 
+     } 
+
+     // print the constructed distance array 
+     printSolution(dist, V); 
+} 
+
+// driver program to test above function 
+int main() 
+{ 
+   /* Let us create the example graph discussed above */
+   int graph[V][V] = {{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); 
+
+    return 0; 
+}