Create isBipartiteGraph.hpp

include/CXXGraph/Graph/Algorithm/isBipartiteGraph.hpp

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+/***********************************************************/
+/***      ______  ____  ______                 _         ***/
+/***     / ___\ \/ /\ \/ / ___|_ __ __ _ _ __ | |__      ***/
+/***    | |    \  /  \  / |  _| '__/ _` | '_ \| '_ \     ***/
+/***    | |___ /  \  /  \ |_| | | | (_| | |_) | | | |    ***/
+/***     \____/_/\_\/_/\_\____|_|  \__,_| .__/|_| |_|    ***/
+/***                                    |_|             ***/
+/***********************************************************/
+/***     Header-Only C++ Library for Graph               ***/
+/***   Representation and Algorithms                     ***/
+/***********************************************************/
+/***     Author: ZigRazor ***/
+/***    E-Mail: [email protected]                       ***/
+/***********************************************************/
+/***    Collaboration: -----------                       ***/
+/***********************************************************/
+/***    License: AGPL v3.0 ***/
+/***********************************************************/
+
+#ifndef __CXXGRAPH_CHECK_ODD_NODES_CYCLE_H__
+#define __CXXGRAPH_CHECK_ODD_NODES_CYCLE_H__
+
+#pragma once
+
+#include "CXXGraph/Graph/Graph_decl.h"
+
+namespace CXXGraph {
+
+template <typename T>
+class Graph {
+public:
+    TopoSortResult<T> checkOddNodesCycleDir() const;
+
+private:
+    void checkOddNodesCycleUtil(std::vector<int>& visited, std::vector<int>& chainNo, 
+                                int root, int cycleLength, bool &isBiPartite) const;
+};
+
+template <typename T>
+TopoSortResult<T> Graph<T>::checkOddNodesCycleDir() const {
+    TopoSortResult<T> result;
+
+    // Check if the graph is undirected
+    if (isDirectedGraph()) {
+        result.errorMessage = ERR_UNDIR_GRAPH; // Error: Graph is directed
+        return result;
+    }
+
+    const auto nodeSet = Graph<T>::getNodeSet();
+    std::vector<int> visited(nodeSet.size(), 0);
+    std::vector<int> chainNo(nodeSet.size(), -1);
+    bool isBiPartite = true;
+
+    for (const auto& node : nodeSet) {
+        if (!visited[node->getId()]) {
+            visited[node->getId()] = 1;
+            checkOddNodesCycleUtil(visited, chainNo, node->getId(), 0, isBiPartite);
+            if (!isBiPartite) {
+                result.errorMessage = "The graph contains an odd-length cycle.";
+                return result;
+            }
+        }
+    }
+
+    result.success = true;
+    return result;
+}
+
+template <typename T>
+void Graph<T>::checkOddNodesCycleUtil(std::vector<int>& visited, std::vector<int>& chainNo, 
+                                      int root, int cycleLength, bool &isBiPartite) const {
+    chainNo[root] = cycleLength;
+    for (const auto& child : cachedAdjMatrix->find(root)) {
+        if (!visited[std::get<0>(child)->getId()]) {
+            visited[std::get<0>(child)->getId()] = 1;
+            checkOddNodesCycleUtil(visited, chainNo, std::get<0>(child)->getId(), cycleLength + 1, isBiPartite);
+            if (!isBiPartite) return;
+        } else if (chainNo[root] == chainNo[std::get<0>(child)->getId()]) {
+            isBiPartite = false;
+            return;
+        }
+    }
+}
+
+}  // namespace CXXGraph
+
+#endif  // __CXXGRAPH_CHECK_ODD_NODES_CYCLE_H__

test/BipartiteTest.cpp

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+#include <memory>
+
+#include "CXXGraph/CXXGraph.hpp"
+#include "gtest/gtest.h"
+
+// Smart pointers alias
+template <typename T>
+using unique = std::unique_ptr<T>;
+template <typename T>
+using shared = std::shared_ptr<T>;
+
+using std::make_shared;
+using std::make_unique;
+
+TEST(IsBipartiteTest, bipartite_graph) {
+  // Bipartite graph
+  CXXGraph::Node<int> node1("1", 1);
+  CXXGraph::Node<int> node2("2", 2);
+  CXXGraph::Node<int> node3("3", 3);
+  CXXGraph::Node<int> node4("4", 4);
+
+  CXXGraph::UndirectedEdge<int> edge1(1, node1, node2);
+  CXXGraph::UndirectedEdge<int> edge2(2, node1, node3);
+  CXXGraph::UndirectedEdge<int> edge3(3, node3, node4);
+  CXXGraph::UndirectedEdge<int> edge4(4, node2, node4);
+
+  CXXGraph::T_EdgeSet<int> edgeSet;
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge1));
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge2));
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge3));
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge4));
+
+  CXXGraph::Graph<int> graph(edgeSet);
+
+  bool isBipartite = graph.isBipartite();
+  ASSERT_EQ(isBipartite, true);  // This graph is bipartite
+}
+
+TEST(IsBipartiteTest, non_bipartite_graph) {
+  // Non-bipartite graph with odd cycle
+  CXXGraph::Node<int> node1("1", 1);
+  CXXGraph::Node<int> node2("2", 2);
+  CXXGraph::Node<int> node3("3", 3);
+
+  CXXGraph::UndirectedEdge<int> edge1(1, node1, node2);
+  CXXGraph::UndirectedEdge<int> edge2(2, node2, node3);
+  CXXGraph::UndirectedEdge<int> edge3(3, node3, node1);  // Forms a cycle of 3 nodes
+
+  CXXGraph::T_EdgeSet<int> edgeSet;
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge1));
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge2));
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge3));
+
+  CXXGraph::Graph<int> graph(edgeSet);
+
+  bool isBipartite = graph.isBipartite();
+  ASSERT_EQ(isBipartite, false);  // This graph has an odd-length cycle, so it's not bipartite
+}
+
+TEST(IsBipartiteTest, empty_graph) {
+  // Empty graph
+  CXXGraph::T_EdgeSet<int> edgeSet;
+  CXXGraph::Graph<int> graph(edgeSet);
+
+  bool isBipartite = graph.isBipartite();
+  ASSERT_EQ(isBipartite, true);  // An empty graph is trivially bipartite
+}
+
+TEST(IsBipartiteTest, single_node_graph) {
+  // Single node graph (trivially bipartite)
+  CXXGraph::Node<int> node1("1", 1);
+  CXXGraph::T_EdgeSet<int> edgeSet;
+  CXXGraph::Graph<int> graph(edgeSet);
+
+  bool isBipartite = graph.isBipartite();
+  ASSERT_EQ(isBipartite, true);  // A graph with a single node is bipartite
+}
+
+TEST(IsBipartiteTest, complex_bipartite_graph) {
+  // More complex bipartite graph
+  CXXGraph::Node<int> node1("1", 1);
+  CXXGraph::Node<int> node2("2", 2);
+  CXXGraph::Node<int> node3("3", 3);
+  CXXGraph::Node<int> node4("4", 4);
+  CXXGraph::Node<int> node5("5", 5);
+  CXXGraph::Node<int> node6("6", 6);
+
+  CXXGraph::UndirectedEdge<int> edge1(1, node1, node2);
+  CXXGraph::UndirectedEdge<int> edge2(2, node1, node3);
+  CXXGraph::UndirectedEdge<int> edge3(3, node4, node5);
+  CXXGraph::UndirectedEdge<int> edge4(4, node4, node6);
+  CXXGraph::UndirectedEdge<int> edge5(5, node2, node4);
+  CXXGraph::UndirectedEdge<int> edge6(6, node3, node5);
+
+  CXXGraph::T_EdgeSet<int> edgeSet;
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge1));
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge2));
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge3));
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge4));
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge5));
+  edgeSet.insert(make_shared<CXXGraph::UndirectedEdge<int>>(edge6));
+
+  CXXGraph::Graph<int> graph(edgeSet);
+
+  bool isBipartite = graph.isBipartite();
+  ASSERT_EQ(isBipartite, true);  // This graph is bipartite
+}