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pub mod bfs {
use std::usize;
use std::{
collections::{HashSet, VecDeque},
io::{stdin, stdout, Write},
};
/// A graph data structure with adjacency list representation.
pub struct Graph {
/// The edges of the graph stored as adjacency lists.
pub edges: Vec<Vec<usize>>,
/// The total number of vertices in the graph.
pub vertices: usize,
}
impl Graph {
pub fn new(vertices: usize) -> Self {
Graph {
edges: vec![Vec::new(); vertices],
vertices,
}
}
/// Adds an edge between two vertices in the graph.
///
/// # Arguments
///
/// * `u` - The index of the first vertex.
/// * `v` - The index of the second vertex.
///
/// # Example
///
/// ```
/// use my_crate::Graph;
///
/// let mut graph = Graph::new(5);
///
/// graph.add_edge(0, 1);
/// graph.add_edge(1, 2);
/// graph.add_edge(2, 3);
/// graph.add_edge(3, 4);
///
pub fn add_edge(&mut self, u: usize, v: usize) {
self.edges[u].push(v);
//for undirected graphs
self.edges[v].push(u);
}
///BFS algorithm
/// Performs a Breadth-First Search on a given graph represented as an adjacency list and returns visited vertices in the order they were visited.
///
/// # Arguments
///
/// * adj_list - A graph represented as an adjacency list. Each vector in the adjacency list represents the vertices that the corresponding vertex has an outgoing edge to.
/// * start - The index of the vertex to start the Breadth-First Search from.
///
/// # Returns
///
/// * visited - A vector of visited vertices in the order they were visited during the Breadth-First Search.
///
/// # Example
///```
/// use breadth_first_search::bfs;
///
/// let adj_list = vec![
/// vec![1, 2], // Node 0 has edges to nodes 1 and 2
/// vec![3, 4], // Node 1 has edges to nodes 3 and 4
/// vec![5], // Node 2 has edge to node 5
/// vec![6], // Node 3 has edge to node 6
/// vec![], // Node 4 has no outgoing edges
/// vec![7, 8], // Node 5 has edges to nodes 7 and 8
/// vec![], // Node 6 has no outgoing edges
/// vec![9], // Node 7 has edge to node 9
/// vec![], // Node 8 has no outgoing edges
/// vec![], // Node 9 has no outgoing edges
/// ];
/// let start_vertex = 0;
///
/// let visited = bfs(&adj_list, start_vertex);
///
/// assert_eq!(visited, vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
///
pub fn b_fs(&self, start: usize) -> Vec<usize> {
let mut visited = HashSet::new();
let mut queue = VecDeque::new();
let mut visited_vec = Vec::new();
visited.insert(start);
queue.push_back(start);
while let Some(u) = queue.pop_front() {
println!("Visited node: {}", u);
visited_vec.push(u);
for &v in &self.edges[u] {
if !visited.contains(&v) {
visited.insert(v);
queue.push_back(v);
}
}
}
visited_vec
}
}
/// Performs Breadth First Search algorithm on a given graph represented as an adjacency list.
/// Prints a graph, where each inner vector contains the nodes of a strongly connected component in sorted order.
///
/// # Input
/// * `no_of_vertices` - Input the number of vertices in the graph
/// * `no_of_edges` - Input the number of edges in the graph
/// * `source` - The source vertex of an edge in the graph
/// * `destination` - The destination of an edge in the graph
/// * `Start_vertex` - The start vertex where BFS algorithm starts from
///
/// # Output
///
/// Prints the visit order of the vertices of the graph
///
/// # Sample input
/// ```
/// Please Enter Number of Vertices : 5
///Please Enter Number of edges in the graph : 5
///Source : 0
///Destination : 1
///Source : 0
///Destination : 2
///Source : 0
///Destination : 3
///Source : 2
///Destination : 1
///Source : 2
///Destination : 4
///Enter Starting Vertex : 0
/// ```
/// # Sample output
/// ```
/// Visited node: 0
/// Visited node: 1
/// Visited node: 2
/// Visited node: 3
/// Visited node: 4
/// ```
pub fn bfs() {
//read the number of vertices from the console
let mut vertex = String::new();
println!("*****BFS********");
println!("****************************************************");
//get the number of vertices
print!("Please Enter Number of Vertices : ");
let _ = stdout().flush();
stdin()
.read_line(&mut vertex)
.expect("Enter valid number of vertices");
let vertices: usize = vertex.trim().parse().expect("Invalid input");
//get number of edges in the graph
let mut n_edges = String::new();
print!("Please Enter Number of edges in the graph : ");
let _ = stdout().flush();
stdin().read_line(&mut n_edges).expect("Enter Valid Input");
let n_edges: i32 = n_edges.trim().parse().expect("Invalid input for source");
//assign the vertices to each edge from the console
let g = add_edges(vertices, n_edges);
//get the source vertex
let mut start = String::new();
print!("Enter Starting Vertex : ");
let _ = stdout().flush();
stdin()
.read_line(&mut start)
.expect("Enter valid starting vertex ");
let start: usize = start
.trim()
.parse()
.expect("Invalid input for starting vertex");
//call BFS implementation
g.b_fs(start);
}
//to return the vertices of each edge as a graph
pub fn add_edges(vertices: usize, edges: i32) -> Graph {
//intialize a new graph with the required number of vertices
let mut g = Graph::new(vertices);
for _i in 0..(edges) {
//intialize source and destination
let mut s = String::new();
let mut d = String::new();
//get the source
print!("Source : ");
let _ = stdout().flush();
stdin()
.read_line(&mut s)
.expect("Please Enter Valid Input for .");
let s: usize = s.trim().parse().expect("Invalid input for source");
//get the destination
print!("Destination : ");
let _ = stdout().flush();
stdin()
.read_line(&mut d)
.expect("Please Enter Valid Input for .");
let d: usize = d.trim().parse().expect("Invalid input for source");
//add edge with source and destination
g.add_edge(s, d);
//for undirected graphs
g.add_edge(d, s);
}
//return graph in the form containing vertices of the
return g;
}
}
#[cfg(test)]
mod tests {
use super::bfs::*;
#[test]
fn test_new_graph() {
let g = Graph::new(5);
assert_eq!(g.vertices, 5);
assert_eq!(g.edges.len(), 5);
}
#[test]
fn test_add_edge() {
let mut g = Graph::new(5);
g.add_edge(0, 1);
g.add_edge(0, 2);
g.add_edge(1, 3);
g.add_edge(2, 4);
//Run the BFS algorithm starting from vertex 2
let visited = g.b_fs(0);
//Check that the visited nodes match the expected set
let expected = vec![0, 1, 2, 3, 4];
assert_eq!(visited, expected);
assert!(visited.contains(&0));
assert!(visited.contains(&1));
assert!(visited.contains(&2));
assert!(visited.contains(&3));
assert!(visited.contains(&4));
assert_eq!(visited.len(), 5);
}
#[test]
fn test_bfs() {
//Create a new graph with 5 vertices
let mut g = Graph::new(5);
//Add edges to the graph
g.add_edge(0, 1);
g.add_edge(0, 2);
g.add_edge(1, 2);
g.add_edge(2, 0);
g.add_edge(2, 3);
g.add_edge(3, 3);
//Run the BFS algorithm starting from vertex 2
let visited = g.b_fs(2);
//Check that the visited nodes match the expected set
let expected = vec![2, 0, 1, 3];
assert_eq!(visited, expected);
assert!(visited.contains(&0));
assert!(visited.contains(&1));
assert!(visited.contains(&2));
assert!(visited.contains(&3));
assert_eq!(visited.len(), 4);
}
}