Create Dijkstra’s Shortest Path Algorithm.js

Dijkstra’s Shortest Path Algorithm.js

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+// A Javascript program for Dijkstra's single
+// source shortest path algorithm.
+// The program is for adjacency matrix
+// representation of the graph	
+let 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
+function minDistance(dist,sptSet)
+{
+
+	// Initialize min value
+	let min = Number.MAX_VALUE;
+	let min_index = -1;
+
+	for(let 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
+function printSolution(dist)
+{
+	document.write("Vertex \t\t Distance from Source<br>");
+	for(let i = 0; i < V; i++)
+	{
+		document.write(i + " \t\t " +
+				dist[i] + "<br>");
+	}
+}
+
+// Function that implements Dijkstra's
+// single source shortest path algorithm
+// for a graph represented using adjacency
+// matrix representation
+function dijkstra(graph, src)
+{
+	let dist = new Array(V);
+	let sptSet = new Array(V);
+
+	// Initialize all distances as
+	// INFINITE and stpSet[] as false
+	for(let i = 0; i < V; i++)
+	{
+		dist[i] = Number.MAX_VALUE;
+		sptSet[i] = false;
+	}
+
+	// Distance of source vertex
+	// from itself is always 0
+	dist[src] = 0;
+
+	// Find shortest path for all vertices
+	for(let 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 first iteration.
+		let 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(let 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] != 0 &&
+				dist[u] != Number.MAX_VALUE &&
+				dist[u] + graph[u][v] < dist[v])
+			{
+				dist[v] = dist[u] + graph[u][v];
+			}
+		}
+	}
+
+	// Print the constructed distance array
+	printSolution(dist);
+}
+
+// Driver code
+let 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);
+