graph Namespace Reference

Graph algorithms. More...

Functions
void	add_directed_edge (std::vector< std::vector< int >> *graph, int u, int v)
	Adds a directed edge from vertex u to vertex v. More...
void	add_undirected_edge (std::vector< std::vector< int >> *graph, int u, int v)
	Adds an undirected edge from vertex u to vertex v. Essentially adds too directed edges to the adjacency list reprsentation of the graph. More...
std::vector< bool >	breadth_first_search (const std::vector< std::vector< int >> &graph, int start)
	Function performs the breadth first search algorithm over the graph. More...

Detailed Description

Graph algorithms.

Function Documentation

add_directed_edge()

void graph::add_directed_edge	(	std::vector< std::vector< int >> *	graph,
		int	u,
		int	v
	)

Adds a directed edge from vertex u to vertex v.

Parameters

graph	Adjacency list representation of graph
u	first vertex
v	second vertex

                                                                       {
    (*graph)[u].push_back(v);
}

add_undirected_edge()

void graph::add_undirected_edge	(	std::vector< std::vector< int >> *	graph,
		int	u,
		int	v
	)

Adds an undirected edge from vertex u to vertex v. Essentially adds too directed edges to the adjacency list reprsentation of the graph.

Parameters

graph	Adjacency list representation of graph
u	first vertex
v	second vertex

                                                                         {
    add_directed_edge(graph, u, v);
    add_directed_edge(graph, v, u);
}

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breadth_first_search()

std::vector<bool> graph::breadth_first_search	(	const std::vector< std::vector< int >> &	graph,
		int	start
	)

Function performs the breadth first search algorithm over the graph.

Parameters

graph	Adjacency list representation of graph
start	vertex from where traversing starts

Returns

a binary vector indicating which vertices were visited during the search.

vector to keep track of visited vertices

a queue that stores vertices that need to be further explored

mark the starting vertex as visited

if the vertex is not visited then mark it as visited and push it to the queue

                                                 {
    /// vector to keep track of visited vertices
    std::vector<bool> visited(graph.size(), false);
    /// a queue that stores vertices that need to be further explored
    std::queue<int> tracker;
 
    /// mark the starting vertex as visited
    visited[start] = true;
    tracker.push(start);
    while (!tracker.empty()) {
        size_t vertex = tracker.front();
        tracker.pop();
        for (auto x : graph[vertex]) {
            /// if the vertex is not visited then mark it as visited
            /// and push it to the queue
            if (!visited[x]) {
                visited[x] = true;
                tracker.push(x);
            }
        }
    }
    return visited;
}

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