test: DAG shortest path test added

Author: Debashis08

SourceCodes/0003_Graph/0003_TopologicalSort.cc

@@ -36,7 +36,7 @@ namespace TopologicalSort
 		this->time++;
 		nodeU->discoveryTime = this->time;
 		nodeU->color = GRAY;
-		for (auto nodeV : this->_adjlist[nodeU])
+		for (auto& nodeV : this->_adjlist[nodeU])
 		{
 			if (nodeV->color == WHITE)
 			{

SourceCodes/0003_Graph/0009_SingleSourceShortestPathBellmanFord.cc

@@ -46,7 +46,7 @@ namespace SingleSourceShortestPathBellmanFord
 
 	void Graph::Relax(Edge* edge)
 	{
-		if (edge->nodeV->distance > (edge->nodeU->distance + edge->weight))
+		if (edge->nodeU->distance != INT_MAX && (edge->nodeV->distance > (edge->nodeU->distance + edge->weight)))
 		{
 			edge->nodeV->distance = edge->nodeU->distance + edge->weight;
 			edge->nodeV->parent = edge->nodeU;

SourceCodes/0003_Graph/0010_DirectedAcyclicGraphShortestPath.cc

@@ -38,11 +38,10 @@ namespace DirectedAcyclicGraphShortestPath
 	void Graph::DepthFirstSearch(Node* nodeU)
 	{
 		nodeU->color = GRAY;
-		for (auto nodeV : this->_adjlist[nodeU])
+		for (auto& nodeV : this->_adjlist[nodeU])
 		{
 			if (nodeV->color == WHITE)
 			{
-				nodeV->parent = nodeU;
 				this->DepthFirstSearch(nodeV);
 			}
 		}
@@ -73,7 +72,7 @@ namespace DirectedAcyclicGraphShortestPath
 
 	void Graph::Relax(Edge* edge)
 	{
-		if (edge->nodeV->distance > (edge->nodeU->distance + edge->weight))
+		if (edge->nodeU->distance != INT_MAX && (edge->nodeV->distance > (edge->nodeU->distance + edge->weight)))
 		{
 			edge->nodeV->distance = edge->nodeU->distance + edge->weight;
 			edge->nodeV->parent = edge->nodeU;

Tests/0003_Graph/0010_DirectedAcyclicGraphShortestPathTest.cc

@@ -0,0 +1,29 @@
+#include<gtest/gtest.h>
+#include "../Headers/0003_Graph/0010_DirectedAcyclicGraphShortestPath.h"
+#include "../0000_CommonUtilities/UnitTestHelper.h"
+
+namespace DirectedAcyclicGraphShortestPath
+{
+	UnitTestHelper unitTestHelper;
+
+	// Test for Simple Graph
+	TEST(DAGTest, SimpleGraph)
+	{
+		Graph graph;
+
+		graph.PushDirectedEdge(0, 1, 5);
+		graph.PushDirectedEdge(0, 2, 3);
+		graph.PushDirectedEdge(1, 2, 2);
+		graph.PushDirectedEdge(1, 3, 6);
+		graph.PushDirectedEdge(2, 3, 7);
+		graph.PushDirectedEdge(2, 4, 4);
+		graph.PushDirectedEdge(2, 5, 2);
+		graph.PushDirectedEdge(3, 4, -1);
+		graph.PushDirectedEdge(3, 5, 1);
+		graph.PushDirectedEdge(4, 5, -2);
+
+		graph.FindDAGShortestPath(1);
+		string expectedPath = "1 3 4 5";
+		ASSERT_EQ(unitTestHelper.SerializeVectorToString(graph.GetDAGShortestPath(5)), expectedPath);
+	}
+}