Merge pull request #37 from Debashis08/feature-graph-implementation

feature-test: dijkstra logic, test added

Author: Debashis08

Headers/0003_Graph/0011_SingleSourceShortestPathDijkstra.h

@@ -0,0 +1,55 @@
+#pragma once
+
+#include<map>
+#include<vector>
+#include<set>
+using namespace std;
+
+namespace SingleSourceShortestPathDijkstra
+{
+	class Node
+	{
+	public:
+		int data;
+		int distance;
+		Node* parent;
+		Node(int data);
+	};
+
+	class Edge
+	{
+	public:
+		Node* nodeU;
+		Node* nodeV;
+		int weight;
+		Edge(Node* nodeU, Node* nodeV, int weight);
+	};
+
+	class CompareNodeDistance
+	{
+	public:
+		bool operator()(const Node* nodeU, const Node* nodeV) const
+		{
+			return nodeU->distance < nodeV->distance;
+		}
+	};
+
+	class Graph
+	{
+	private:
+		map<Node*, vector<Node*>> _adjlist;
+		map<int, Node*> _nodeMap;
+		map<Node*, vector<Edge*>> _edgeMap;
+		multiset<Node*, CompareNodeDistance> _operationalSet;
+		Node* MakeOrFindNode(int data);
+		void InitializeSingleSource(Node* sourceNode);
+		void Relax(Edge* edge);
+		void Dijkstra(Node* source);
+		void GetShortestPath(Node* node, vector<int>& path);
+
+	public:
+		void PushDirectedEdge(int valueU, int valueV, int weight);
+		void FindShortestPathDijkstra(int data);
+		vector<int> GetDijkstraShortestPath(int data);
+	};
+}

SourceCodes/0003_Graph/0011_SingleSourceShortestPathDijkstra.cc

@@ -0,0 +1,113 @@
+#include "../Headers/0003_Graph/0011_SingleSourceShortestPathDijkstra.h"
+#include<climits>
+#include<algorithm>
+using namespace std;
+
+namespace SingleSourceShortestPathDijkstra
+{
+	Node::Node(int data)
+	{
+		this->data = data;
+		this->distance = INT_MAX;
+		this->parent = nullptr;
+	}
+
+	Edge::Edge(Node* nodeU, Node* nodeV, int weight)
+	{
+		this->nodeU = nodeU;
+		this->nodeV = nodeV;
+		this->weight = weight;
+	}
+
+	// Graph Private Member Methods
+	Node* Graph::MakeOrFindNode(int data)
+	{
+		Node* node = nullptr;
+		if (this->_nodeMap.find(data) == this->_nodeMap.end())
+		{
+			node = new Node(data);
+			this->_nodeMap[data] = node;
+		}
+		else
+		{
+			node = this->_nodeMap[data];
+		}
+		return node;
+	}
+
+	void Graph::InitializeSingleSource(Node* sourceNode)
+	{
+		for (auto& iterator : this->_nodeMap)
+		{
+			iterator.second->distance = INT_MAX;
+			iterator.second->parent = nullptr;
+		}
+		sourceNode->distance = 0;
+	}
+
+	void Graph::Relax(Edge* edge)
+	{
+		if (edge->nodeU->distance != INT_MAX && (edge->nodeV->distance > (edge->nodeU->distance + edge->weight)))
+		{
+			this->_operationalSet.erase(edge->nodeV);
+			edge->nodeV->distance = edge->nodeU->distance + edge->weight;
+			edge->nodeV->parent = edge->nodeU;
+			this->_operationalSet.insert(edge->nodeV);
+		}
+	}
+
+	void Graph::Dijkstra(Node* source)
+	{
+		this->InitializeSingleSource(source);
+
+		for (auto& node : this->_nodeMap)
+		{
+			this->_operationalSet.insert(node.second);
+		}
+
+		while (!this->_operationalSet.empty())
+		{
+			Node* nodeU = *(this->_operationalSet.begin());
+			this->_operationalSet.erase(nodeU);
+
+			for (auto& edge : this->_edgeMap[nodeU])
+			{
+				this->Relax(edge);
+			}
+		}
+	}
+
+	void Graph::GetShortestPath(Node* node, vector<int>& path)
+	{
+		path.push_back(node->data);
+		if (node->parent != nullptr)
+		{
+			this->GetShortestPath(node->parent, path);
+		}
+	}
+
+	// Graph Public Member Methods
+	void Graph::PushDirectedEdge(int dataU, int dataV, int weight)
+	{
+		Node* nodeU = this->MakeOrFindNode(dataU);
+		Node* nodeV = this->MakeOrFindNode(dataV);
+
+		this->_adjlist[nodeU].push_back(nodeV);
+		this->_edgeMap[nodeU].push_back(new Edge(nodeU, nodeV, weight));
+	}
+	
+	void Graph::FindShortestPathDijkstra(int data)
+	{
+		Node* source = this->_nodeMap[data];
+		this->Dijkstra(source);
+	}
+
+	vector<int> Graph::GetDijkstraShortestPath(int data)
+	{
+		vector<int> path = {};
+		Node* node = this->_nodeMap[data];
+		this->GetShortestPath(node, path);
+		reverse(path.begin(), path.end());
+		return path;
+	}
+}

SourceCodes/0003_Graph/CMakeLists.txt

@@ -10,6 +10,7 @@ set(0003GRAPH_SOURCES
     0008_MinimumSpanningTreePrimAlgorithm.cc
     0009_SingleSourceShortestPathBellmanFord.cc
     0010_DirectedAcyclicGraphShortestPath.cc
+    0011_SingleSourceShortestPathDijkstra.cc
 
 )
 

Tests/0003_Graph/0011_SingleSourceShortestPathDijkstraTest.cc

@@ -0,0 +1,31 @@
+#include<gtest/gtest.h>
+#include "../Headers/0003_Graph/0011_SingleSourceShortestPathDijkstra.h"
+#include "../0000_CommonUtilities/UnitTestHelper.h"
+
+namespace SingleSourceShortestPathDijkstra
+{
+	UnitTestHelper unitTestHelper;
+
+	// Test for Simple Graph
+	TEST(DijkstraTest, SimpleGraph)
+	{
+		Graph graph;
+
+		graph.PushDirectedEdge(0, 1, 10);
+		graph.PushDirectedEdge(0, 3, 5);
+		graph.PushDirectedEdge(1, 2, 1);
+		graph.PushDirectedEdge(1, 3, 2);
+		graph.PushDirectedEdge(2, 4, 4);
+		graph.PushDirectedEdge(3, 1, 3);
+		graph.PushDirectedEdge(3, 2, 9);
+		graph.PushDirectedEdge(3, 4, 2);
+		graph.PushDirectedEdge(4, 2, 6);
+		graph.PushDirectedEdge(4, 0, 7);
+
+		graph.FindShortestPathDijkstra(0);
+
+		string expectedPath = "0 3 1 2";
+
+		ASSERT_EQ(unitTestHelper.SerializeVectorToString(graph.GetDijkstraShortestPath(2)), expectedPath);
+	}
+}

Tests/0003_Graph/CMakeLists.txt

@@ -22,6 +22,7 @@ add_executable(
   0008_MinimumSpanningTreePrimAlgorithmTest.cc
   0009_SingleSourceShortestPathBellmanFordTest.cc
   0010_DirectedAcyclicGraphShortestPathTest.cc
+  0011_SingleSourceShortestPathDijkstraTest.cc
 )
 
 target_link_libraries(