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feat: Define graph structure in breadth_first_search (#1076)

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* feat: Define graph structure in breadth_first_search

* using instead of typedef
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Filip Hlasek 2020-09-18 10:34:18 -07:00 committed by GitHub
parent 88fe6911df
commit d4b54b8294
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1 changed files with 20 additions and 8 deletions
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28
graph/breadth_first_search.cpp
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@ -54,6 +54,17 @@
* \brief Graph algorithms * \brief Graph algorithms
*/ */
namespace graph { namespace graph {
/**
* \brief Representation of the graph as an adjacency list.
*
* For every vertex, there is a list of its neighbors in the order in which
* they were added to the graph. By default, the edges are directed, but
* an undirected graph can be represented simply by storing each each as
* two directed edges in both directions.
*/
using adjacency_list = std::vector<std::vector<int>>;
/** /**
* \brief * \brief
* Adds a directed edge from vertex u to vertex v. * Adds a directed edge from vertex u to vertex v.
@ -63,7 +74,7 @@ namespace graph {
* @param v second vertex * @param v second vertex
* *
*/ */
void add_directed_edge(std::vector<std::vector<int>> *graph, int u, int v) { void add_directed_edge(adjacency_list *graph, int u, int v) {
(*graph)[u].push_back(v); (*graph)[u].push_back(v);
} }
@ -78,7 +89,7 @@ void add_directed_edge(std::vector<std::vector<int>> *graph, int u, int v) {
* @param v second vertex * @param v second vertex
* *
*/ */
void add_undirected_edge(std::vector<std::vector<int>> *graph, int u, int v) { void add_undirected_edge(adjacency_list *graph, int u, int v) {
add_directed_edge(graph, u, v); add_directed_edge(graph, u, v);
add_directed_edge(graph, v, u); add_directed_edge(graph, v, u);
} }
@ -93,11 +104,10 @@ void add_undirected_edge(std::vector<std::vector<int>> *graph, int u, int v) {
* search. * search.
* *
*/ */
std::vector<bool> breadth_first_search( std::vector<bool> breadth_first_search(const adjacency_list &graph, int start) {
const std::vector<std::vector<int>> &graph, int start) {
/// vector to keep track of visited vertices /// vector to keep track of visited vertices
std::vector<bool> visited(graph.size(), false); std::vector<bool> visited(graph.size(), false);
/// a queue that stores vertices that need to be further explored /// queue that stores vertices that need to be further explored
std::queue<int> tracker; std::queue<int> tracker;
/// mark the starting vertex as visited /// mark the starting vertex as visited
@ -117,11 +127,13 @@ std::vector<bool> breadth_first_search(
} }
return visited; return visited;
} }
} // namespace graph } // namespace graph
void tests() { /** Test function */
static void tests() {
/// Test 1 Begin /// Test 1 Begin
std::vector<std::vector<int>> graph(4, std::vector<int>()); graph::adjacency_list graph(4, std::vector<int>());
graph::add_undirected_edge(&graph, 0, 1); graph::add_undirected_edge(&graph, 0, 1);
graph::add_undirected_edge(&graph, 1, 2); graph::add_undirected_edge(&graph, 1, 2);
graph::add_undirected_edge(&graph, 2, 3); graph::add_undirected_edge(&graph, 2, 3);
@ -168,7 +180,7 @@ int main() {
std::cout << "Enter the number of edges: "; std::cout << "Enter the number of edges: ";
std::cin >> edges; std::cin >> edges;
std::vector<std::vector<int>> graph(vertices); graph::adjacency_list graph(vertices);
std::cout << "Enter space-separated pairs of vertices that form edges: " std::cout << "Enter space-separated pairs of vertices that form edges: "
<< std::endl; << std::endl;