From 3239fcc19ea01f297707ee1f854bc6a6382f9e24 Mon Sep 17 00:00:00 2001 From: Filip Hlasek Date: Thu, 27 Aug 2020 07:26:49 -0700 Subject: [PATCH] fix: linter and spacing for is_graph_bipartite. (#1037) * fix: linter and spacing for is_graph_bipartite. * updating DIRECTORY.md * clang-tidy fixes for a49ec9b8d79e62be49587043cf482a9f705e3ed1 * clang-format and clang-tidy fixes for 40a56d2f * Address reviewer's comments. * Fix docs wording. Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com> --- graph/is_graph_bipartite.cpp | 278 ++++++++++++++++++----------------- 1 file changed, 143 insertions(+), 135 deletions(-) diff --git a/graph/is_graph_bipartite.cpp b/graph/is_graph_bipartite.cpp index baadf71f..2772117f 100644 --- a/graph/is_graph_bipartite.cpp +++ b/graph/is_graph_bipartite.cpp @@ -1,163 +1,171 @@ /** - * @file + * @file * - * @brief Algorithm to check whether a graph is [bipartite](https://en.wikipedia.org/wiki/Bipartite_graph) - * - * @details - * A graph is a collection of nodes also called vertices and these vertices - * are connected by edges.A bipartite graph is a graph whose vertices can be - * divided into two disjoint and independent sets U and V such that every edge - * connects a vertex in U to one in V. - * - * The given Algorithm will determine whether the given graph is bipartite or not - * - * 
- * 	Example - Here is a graph g1 with 5 vertices and is bipartite
- *	
- *		1   4
- *	   / \ / \
- *	  2   3   5
- *	
- *	Example - Here is a graph G2 with 3 vertices and is not bipartite
- *	
- *		1 --- 2
- *		 \   /
- *		   3
- *	
- *
+ * @brief Algorithm to check whether a graph is + * [bipartite](https://en.wikipedia.org/wiki/Bipartite_graph) + * + * @details + * A graph is a collection of nodes also called vertices and these vertices + * are connected by edges. A graph is bipartite if its vertices can be + * divided into two disjoint and independent sets U and V such that every edge + * connects a vertex in U to one in V. + * + * The algorithm implemented in this file determines whether the given graph + * is bipartite or not. + * + * 
+ *  Example - Here is a graph g1 with 5 vertices and is bipartite
+ *
+ *     1   4
+ *    / \ / \
+ *   2   3   5
+ *
+ * Example - Here is a graph G2 with 3 vertices and is not bipartite
+ *
+ *   1 --- 2
+ *    \   /
+ *      3
+ *
+ *
+ * + * @author [Akshat Vaya](https://github.com/AkVaya) * - * @author [Akshat Vaya](https://github.com/AkVaya) - * */ #include -#include #include +#include /** * @namespace graph * @brief Graph algorithms */ -namespace graph{ - /** - * @namespace is_graph_bipartite - * @brief Functions for checking whether a graph is bipartite or not - */ - namespace is_graph_bipartite{ - /** - * @brief Class for representing graph as an adjacency list. - */ - class Graph { - private: - int n; /// size of the graph +namespace graph { +/** + * @namespace is_graph_bipartite + * @brief Functions for checking whether a graph is bipartite or not + */ +namespace is_graph_bipartite { +/** + * @brief Class for representing graph as an adjacency list. + */ +class Graph { + private: + int n; ///< size of the graph - std::vector > adj; /// adj stores the graph as an adjacency list + std::vector > + adj; ///< adj stores the graph as an adjacency list - std::vector side; ///stores the side of the vertex + std::vector side; ///< stores the side of the vertex - static const int nax = 5e5 + 1; + public: + /** + * @brief Constructor that initializes the graph on creation + * @param size number of vertices of the graph + */ + explicit Graph(int size) { + n = size; + adj.resize(n); + side.resize(n, -1); + } + void addEdge(int u, int v); /// function to add edges to our graph - public: - /** - * @brief Constructor that initializes the graph on creation - */ - explicit Graph(int size = nax){ - n = size; - adj.resize(n); - side.resize(n,-1); - } + bool + is_bipartite(); /// function to check whether the graph is bipartite or not +}; - void addEdge(int u, int v); /// function to add edges to our graph +/** + * @brief Function that add an edge between two nodes or vertices of graph + * + * @param u is a node or vertex of graph + * @param v is a node or vertex of graph + */ +void Graph::addEdge(int u, int v) { + adj[u - 1].push_back(v - 1); + adj[v - 1].push_back(u - 1); +} - bool is_bipartite(); /// function to check whether the graph is bipartite or not +/** + * @brief function that checks whether the graph is bipartite or not + * the function returns true if the graph is a bipartite graph + * the function returns false if the graph is not a bipartite graph + * + * @details + * Here, side refers to the two disjoint subsets of the bipartite graph. + * Initially, the values of side are set to -1 which is an unassigned state. A + * for loop is run for every vertex of the graph. If the current edge has no + * side assigned to it, then a Breadth First Search operation is performed. If + * two neighbours have the same side then the graph will not be bipartite and + * the value of check becomes false. If and only if each pair of neighbours have + * different sides, the value of check will be true and hence the graph + * bipartite. + * + * @returns `true` if th graph is bipartite + * @returns `false` otherwise + */ +bool Graph::is_bipartite() { + bool check = true; + std::queue q; + for (int current_edge = 0; current_edge < n; ++current_edge) { + if (side[current_edge] == -1) { + q.push(current_edge); + side[current_edge] = 0; + while (q.size()) { + int current = q.front(); + q.pop(); + for (auto neighbour : adj[current]) { + if (side[neighbour] == -1) { + side[neighbour] = (1 ^ side[current]); + q.push(neighbour); + } else { + check &= (side[neighbour] != side[current]); + } + } + } + } + } + return check; +} +} // namespace is_graph_bipartite +} // namespace graph - }; - /** - * @brief Function that add an edge between two nodes or vertices of graph - * - * @param u is a node or vertex of graph - * @param v is a node or vertex of graph - */ - void Graph::addEdge(int u, int v) { - adj[u-1].push_back(v-1); - adj[v-1].push_back(u-1); - } - /** - * @brief function that checks whether the graph is bipartite or not - * the function returns true if the graph is a bipartite graph - * the function returns false if the graph is not a bipartite graph - * - * @details - * Here, side refers to the two disjoint subsets of the bipartite graph. - * Initially, the values of side are set to -1 which is an unassigned state. A for loop is run for every vertex of the graph. - * If the current edge has no side assigned to it, then a Breadth First Search operation is performed. - * If two neighbours have the same side then the graph will not be bipartite and the value of check becomes false. - * If and only if each pair of neighbours have different sides, the value of check will be true and hence the graph bipartite. - * - */ - bool Graph::is_bipartite(){ - bool check = true; - std::queue q; - for (int current_edge = 0; current_edge < n; ++current_edge) - { - if(side[current_edge] == -1){ - q.push(current_edge); - side[current_edge] = 0; - while(q.size()){ - int current = q.front(); - q.pop(); - for(auto neighbour : adj[current]){ - if(side[neighbour] == -1){ - side[neighbour] = (1 ^ side[current]); - q.push(neighbour); - } - else{ - check &= (side[neighbour] != side[current]); - } - } - } - } - } - return check; - } - } /// namespace is_graph_bipartite -} /// namespace graph /** - * Function to test the above algorithm - * @returns none + * Function to test the above algorithm + * @returns none */ -static void test(){ - graph::is_graph_bipartite::Graph G1(5); /// creating graph G1 with 5 vertices - /// adding edges to the graphs as per the illustrated example - G1.addEdge(1,2); - G1.addEdge(1,3); - G1.addEdge(3,4); - G1.addEdge(4,5); +static void test() { + graph::is_graph_bipartite::Graph G1( + 5); /// creating graph G1 with 5 vertices + /// adding edges to the graphs as per the illustrated example + G1.addEdge(1, 2); + G1.addEdge(1, 3); + G1.addEdge(3, 4); + G1.addEdge(4, 5); - graph::is_graph_bipartite::Graph G2(3); /// creating graph G2 with 3 vertices - /// adding edges to the graphs as per the illustrated example - G2.addEdge(1,2); - G2.addEdge(1,3); - G2.addEdge(2,3); + graph::is_graph_bipartite::Graph G2( + 3); /// creating graph G2 with 3 vertices + /// adding edges to the graphs as per the illustrated example + G2.addEdge(1, 2); + G2.addEdge(1, 3); + G2.addEdge(2, 3); - /// checking whether the graphs are bipartite or not - if(G1.is_bipartite()){ - std::cout<<"The given graph G1 is a bipartite graph\n"; - } - else{ - std::cout<<"The given graph G1 is not a bipartite graph\n"; - } - if(G2.is_bipartite()){ - std::cout<<"The given graph G2 is a bipartite graph\n"; - } - else{ - std::cout<<"The given graph G2 is not a bipartite graph\n"; - } + /// checking whether the graphs are bipartite or not + if (G1.is_bipartite()) { + std::cout << "The given graph G1 is a bipartite graph\n"; + } else { + std::cout << "The given graph G1 is not a bipartite graph\n"; + } + if (G2.is_bipartite()) { + std::cout << "The given graph G2 is a bipartite graph\n"; + } else { + std::cout << "The given graph G2 is not a bipartite graph\n"; + } } + /** * Main function */ -int main(){ - test(); ///Testing - return 0; +int main() { + test(); /// Testing + return 0; } -- GitLab