From f5481aa34845a5cc7eba050385a498bc2d5f0fd3 Mon Sep 17 00:00:00 2001
From: Shwetha Neginhal <saneginhal@gmail.com>
Date: Mon, 14 Oct 2019 14:51:08 +0530
Subject: [PATCH] Adding Dijsktra's algorithm in c++

---
 Dijsktra.cpp | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 Dijsktra.cpp

diff --git a/Dijsktra.cpp b/Dijsktra.cpp
new file mode 100644
index 0000000..d717bab
--- /dev/null
+++ b/Dijsktra.cpp
@@ -0,0 +1,88 @@
+// A C++ program for Dijkstra's single source shortest path algorithm. 
+#include <limits.h> 
+#include <stdio.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[]) 
+{ 
+	printf("Vertex \t\t Distance from Source\n"); 
+	for (int i = 0; i < V; i++) 
+		printf("%d \t\t %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 be 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); 
+} 
+
+// 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; 
+}