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@@ -9,3 +9,4 @@ edition = "2021" | |
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[dev-dependencies] | ||
rand = "0.8" | ||
rand_derive2 = "0.1.21" |
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use lctree::LinkCutTree; | ||
use rand::{rngs::StdRng, seq::IteratorRandom, Rng, SeedableRng}; | ||
use rand_derive2::RandGen; | ||
use std::collections::HashSet; | ||
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fn create_random_generator() -> StdRng { | ||
let seed = rand::thread_rng().gen(); | ||
println!("Seed: {}", seed); // print seed so we can reproduce the test (if it fails). | ||
StdRng::seed_from_u64(seed) | ||
} | ||
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fn create_random_tree(rng: &mut StdRng) -> Vec<(usize, usize)> { | ||
let mut nodes = Vec::from([0]); | ||
let mut edges = Vec::new(); | ||
for i in 1..NUMBER_OF_NODES { | ||
let parent = nodes[rng.gen_range(0..i)]; | ||
nodes.push(i); | ||
edges.push((i, parent)); | ||
} | ||
edges | ||
} | ||
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fn dfs( | ||
v: usize, | ||
adj: &Vec<Vec<usize>>, | ||
visited: &mut Vec<bool>, | ||
component_ids: &mut Vec<usize>, | ||
component_id: usize, | ||
) { | ||
visited[v] = true; | ||
component_ids[v] = component_id; | ||
for &w in &adj[v] { | ||
if !visited[w] { | ||
dfs(w, adj, visited, component_ids, component_id); | ||
} | ||
} | ||
} | ||
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fn connected_components(edges: &HashSet<(usize, usize)>) -> Vec<usize> { | ||
// create adjacency list from edges | ||
let mut adj = vec![vec![]; NUMBER_OF_NODES]; | ||
for (v, w) in edges { | ||
adj[*v].push(*w); | ||
adj[*w].push(*v); | ||
} | ||
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// explore each component using dfs and assign component ids | ||
let mut visited = vec![false; NUMBER_OF_NODES]; | ||
let mut component_ids = vec![0; NUMBER_OF_NODES]; | ||
let mut component_id = 0; | ||
for v in 0..NUMBER_OF_NODES { | ||
if !visited[v] { | ||
component_id += 1; | ||
dfs(v, &adj, &mut visited, &mut component_ids, component_id); | ||
} | ||
} | ||
component_ids | ||
} | ||
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const NUMBER_OF_NODES: usize = 100; | ||
const NUMBER_OF_OPERATIONS: usize = 1000; | ||
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#[derive(RandGen)] | ||
enum Operation { | ||
Link, | ||
Cut, | ||
Connected, | ||
} | ||
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#[test] | ||
pub fn test_connectivity() { | ||
let mut rng = create_random_generator(); | ||
let edges = create_random_tree(&mut rng); | ||
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// initialize link-cut tree, we start with a forest of single nodes | ||
// (edges are not added yet): | ||
let mut lctree = LinkCutTree::new(NUMBER_OF_NODES); | ||
let mut edges_in_tree = HashSet::new(); | ||
let mut component_ids = (0..NUMBER_OF_NODES).collect::<Vec<usize>>(); | ||
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// perform random operations: link, cut, or connected: | ||
for _ in 0..NUMBER_OF_OPERATIONS { | ||
let operation: Operation = rng.gen(); | ||
match operation { | ||
Operation::Link => { | ||
let (v, w) = edges.iter().choose(&mut rng).unwrap(); | ||
println!("Link {} {}", v, w); | ||
lctree.link(*v, *w); | ||
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edges_in_tree.insert((*v, *w)); | ||
component_ids = connected_components(&edges_in_tree); | ||
} | ||
Operation::Cut => { | ||
if edges_in_tree.is_empty() { | ||
continue; | ||
} | ||
let (v, w) = edges_in_tree.iter().choose(&mut rng).unwrap(); | ||
println!("Cut {} {}", v, w); | ||
lctree.cut(*v); | ||
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edges_in_tree.remove(&(*v, *w)); | ||
component_ids = connected_components(&edges_in_tree); | ||
} | ||
Operation::Connected => { | ||
let v = rng.gen_range(0..NUMBER_OF_NODES); | ||
let w = rng.gen_range(0..NUMBER_OF_NODES); | ||
println!("Connected {} {}", v, w); | ||
assert_eq!(lctree.connected(v, w), component_ids[v] == component_ids[w]); | ||
} | ||
} | ||
} | ||
} |
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