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pub mod dfs {
//Importng necessary libraries
use std::usize;
use std::{
collections::HashSet,
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 {
// Constructor method for creating a new graph
pub fn new(vertices: usize) -> Self {
Graph {
edges: vec![Vec::new(); vertices], // Initializing adjacency list with empty vectors with size equal to vertices number
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);
}
///DFS algorithm
/// Performs a Depth-First Search on a given graph represented as an adjacency list and returns a vector of 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_vertex` - The index of the vertex to start the Depth-First Search from.
///
/// # Returns
///
/// * `visited` - A vector of visited vertices in the order they were visited during the Depth-First Search.
///
/// # Example
///
/// ```
/// use depth_first_search::dfs;
///
/// 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 = dfs(&adj_list, start_vertex);
///
/// assert_eq!(visited, vec![0, 1, 3, 6, 4, 2, 5, 7, 9, 8]);
/// ```
pub fn d_fs(&self, u: usize, visited: &mut HashSet<usize>) -> Vec<usize> {
visited.insert(u);
println!("Visited node: {}", u);
let mut visited_nodes = vec![u];
for &v in &self.edges[u] {
if !visited.contains(&v) {
visited_nodes.extend(self.d_fs(v, visited));
}
}
visited_nodes
}
}
/// Performs Depth first search algorithm on a given directed graph represented as an adjacency list.
/// Prints a graph, where the nodes of the graph are in the visited 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 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 Source Vertex : 0
/// ```
/// # Sample output
/// ```
///Visited node: 0
///Visited node: 1
///Visited node: 2
///Visited node: 4
///Visited node: 3
///```
pub fn dfs() {
//read the number of vertices from the console
let mut vertex = String::new();
println!("******DFS Traversal*********");
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 source = String::new();
print!("Enter Source Vertex : ");
let _ = stdout().flush();
stdin()
.read_line(&mut source)
.expect("Enter valid source vertex ");
let source: usize = source.trim().parse().expect("Invalid input for source");
//call DFS implementation
let mut visited = HashSet::new();
g.d_fs(source, &mut visited);
}
///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);
g.add_edge(d, s); // for undirected graphs
}
//return graph in the form containing vertices of the
return g;
}
}
#[cfg(test)]
mod tests {
use super::dfs::*;
use std::collections::HashSet;
#[test]
fn test_dfs() {
let mut g = Graph::new(4);
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);
let mut visited = HashSet::new();
let x = g.d_fs(2, &mut visited);
//Check that the visited nodes match the expected set
let expected = vec![2, 0, 1, 3];
assert_eq!(x, expected);
assert!(visited.contains(&0));
assert!(visited.contains(&1));
assert!(visited.contains(&2));
assert!(visited.contains(&3));
assert_eq!(visited.len(), 4);
}
#[test]
fn test_dfs1() {
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);
let mut visited = HashSet::new();
let x = g.d_fs(0, &mut visited);
//Check that the visited nodes match the expected set
let expected = vec![0, 1, 3, 2, 4];
assert_eq!(x, 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);
}
}