topological sorting implementation added

Author: Debashis08

Headers/0003_Graph/0003_TopologicalSort.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include<list>
+#include<map>
+#include<string>
+#include<vector>
+using namespace std;
+enum color { WHITE, GRAY, BLACK };
+
+class TopologicalSortNode
+{
+public:
+    int data;
+    int color;
+    int discoveryTime;
+    int finishingTime;
+    TopologicalSortNode* parent;
+    TopologicalSortNode(int value);
+};
+
+class TopologicalSortGraph
+{
+private:
+    int time;
+    map<TopologicalSortNode*, list<TopologicalSortNode*>> _adjlist;
+    map<int, TopologicalSortNode*> _nodeMap;
+    TopologicalSortNode* MakeOrFindNode(int value);
+    list<TopologicalSortNode*> _topologicalSortedNodeList;
+    void DepthFirstSearch(TopologicalSortNode* DFSNode);
+public:
+    void PushDirectedEdge(int valueU, int valueV);
+    void TopologicalSort();
+    vector<pair<int, pair<int, int>>> ShowTopologicalSortResult();
+};

SourceCodes/0003_Graph/0003_TopologicalSort.cc

@@ -0,0 +1,78 @@
+#include "../Headers/0003_Graph/0003_TopologicalSort.h"
+#include<vector>
+#include<utility>
+#include<climits>
+using namespace std;
+
+TopologicalSortNode::TopologicalSortNode(int value)
+{
+	this->data = value;
+	this->discoveryTime = INT_MAX;
+	this->finishingTime = INT_MAX;
+	this->color = WHITE;
+	this->parent = nullptr;
+}
+
+TopologicalSortNode* TopologicalSortGraph::MakeOrFindNode(int value)
+{
+	TopologicalSortNode* node = nullptr;
+	if (this->_nodeMap.find(value) == this->_nodeMap.end())
+	{
+		node = new TopologicalSortNode(value);
+		this->_nodeMap[value] = node;
+	}
+	else
+	{
+		node = this->_nodeMap[value];
+	}
+	return node;
+}
+
+void TopologicalSortGraph::DepthFirstSearch(TopologicalSortNode* nodeU)
+{
+	this->time++;
+	nodeU->discoveryTime = this->time;
+	nodeU->color = GRAY;
+	for (auto nodeV : this->_adjlist[nodeU])
+	{
+		if (nodeV->color == WHITE)
+		{
+			nodeV->parent = nodeU;
+			this->DepthFirstSearch(nodeV);
+		}
+	}
+	nodeU->color = BLACK;
+	this->time++;
+	nodeU->finishingTime = time;
+	this->_topologicalSortedNodeList.push_front(nodeU);
+}
+
+void TopologicalSortGraph::PushDirectedEdge(int valueU, int valueV)
+{
+	TopologicalSortNode* nodeU = this->MakeOrFindNode(valueU);
+	TopologicalSortNode* nodeV = this->MakeOrFindNode(valueV);
+
+	this->_adjlist[nodeU].push_back(nodeV);
+}
+
+void TopologicalSortGraph::TopologicalSort()
+{
+	this->time = 0;
+	for (auto& iterator : this->_nodeMap)
+	{
+		if (iterator.second->color == WHITE)
+		{
+			this->DepthFirstSearch(iterator.second);
+		}
+	}
+}
+
+vector<pair<int, pair<int, int>>> TopologicalSortGraph::ShowTopologicalSortResult()
+{
+	vector<pair<int, pair<int, int>>> result;
+	for (auto& node : this->_topologicalSortedNodeList)
+	{
+		result.push_back(make_pair(node->data, make_pair(node->discoveryTime, node->finishingTime)));
+	}
+	return result;
+}

SourceCodes/0003_Graph/CMakeLists.txt

@@ -2,6 +2,7 @@
 set(0003GRAPH_SOURCES
     0001_BreadthFirstSearch.cc
     0002_DepthFirstSearch.cc
+    0003_TopologicalSort.cc
 )
 
 # Create a library target

Tests/0003_Graph/0003_TopologicalSortTest.cc

@@ -14,6 +14,7 @@ add_executable(
   0003GraphTests
   0001_BreadthFirstSearchTest.cc
   0002_DepthFirstSearchTest.cc
+  0003_TopologicalSortTest.cc
 )
 
 target_link_libraries(