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|
use std::collections::HashSet;
use std::hash::Hash;
use petgraph::algo::{greedy_matching, maximum_matching};
use petgraph::prelude::*;
macro_rules! assert_one_of {
($actual:expr, [$($expected:expr),+]) => {
let expected = &[$($expected),+];
if !expected.iter().any(|expected| expected == &$actual) {
let expected = expected.iter().map(|e| format!("\n{:?}", e)).collect::<Vec<_>>();
let comma_separated = expected.join(", ");
panic!("assertion failed: `actual does not equal to any of expected`\nactual:\n{:?}\nexpected:{}", $actual, comma_separated);
}
};
}
macro_rules! set {
() => {
HashSet::new()
};
($(($source:expr, $target:expr)),+) => {
{
let mut set = HashSet::new();
$(
set.insert(($source.into(), $target.into()));
)*
set
}
};
($($elem:expr),+) => {
{
let mut set = HashSet::new();
$(
set.insert($elem.into());
)*
set
}
};
}
// So we don't have to type `.collect::<HashSet<_>>`.
fn collect<'a, T: Copy + Eq + Hash + 'a>(iter: impl Iterator<Item = T>) -> HashSet<T> {
iter.collect()
}
#[test]
fn greedy_empty() {
let g: UnGraph<(), ()> = UnGraph::default();
let m = greedy_matching(&g);
assert_eq!(collect(m.edges()), set![]);
assert_eq!(collect(m.nodes()), set![]);
}
#[test]
fn greedy_disjoint() {
let g: UnGraph<(), ()> = UnGraph::from_edges(&[(0, 1), (2, 3)]);
let m = greedy_matching(&g);
assert_eq!(collect(m.edges()), set![(0, 1), (2, 3)]);
assert_eq!(collect(m.nodes()), set![0, 1, 2, 3]);
}
#[test]
fn greedy_odd_path() {
let g: UnGraph<(), ()> = UnGraph::from_edges(&[(0, 1), (1, 2), (2, 3)]);
let m = greedy_matching(&g);
assert_one_of!(collect(m.edges()), [set![(0, 1), (2, 3)], set![(1, 2)]]);
assert_one_of!(collect(m.nodes()), [set![0, 1, 2, 3], set![1, 2]]);
}
#[test]
fn greedy_star() {
let g: UnGraph<(), ()> = UnGraph::from_edges(&[(0, 1), (0, 2), (0, 3)]);
let m = greedy_matching(&g);
assert_one_of!(
collect(m.edges()),
[set![(0, 1)], set![(0, 2)], set![(0, 3)]]
);
assert_one_of!(collect(m.nodes()), [set![0, 1], set![0, 2], set![0, 3]]);
}
#[test]
fn maximum_empty() {
let g: UnGraph<(), ()> = UnGraph::default();
let m = maximum_matching(&g);
assert_eq!(collect(m.edges()), set![]);
assert_eq!(collect(m.nodes()), set![]);
}
#[test]
fn maximum_disjoint() {
let g: UnGraph<(), ()> = UnGraph::from_edges(&[(0, 1), (2, 3)]);
let m = maximum_matching(&g);
assert_eq!(collect(m.edges()), set![(0, 1), (2, 3)]);
assert_eq!(collect(m.nodes()), set![0, 1, 2, 3]);
}
#[test]
fn maximum_odd_path() {
let g: UnGraph<(), ()> = UnGraph::from_edges(&[(0, 1), (1, 2), (2, 3)]);
let m = maximum_matching(&g);
assert_eq!(collect(m.edges()), set![(0, 1), (2, 3)]);
assert_eq!(collect(m.nodes()), set![0, 1, 2, 3]);
}
#[cfg(feature = "stable_graph")]
#[test]
fn maximum_in_stable_graph() {
let mut g: StableUnGraph<(), ()> =
StableUnGraph::from_edges(&[(0, 1), (0, 2), (1, 2), (1, 3), (2, 4), (3, 4), (3, 5)]);
// Create a hole by removing node that would otherwise belong to the maximum
// matching.
g.remove_node(NodeIndex::new(4));
let m = maximum_matching(&g);
assert_one_of!(
collect(m.edges()),
[
set![(0, 1), (3, 5)],
set![(0, 2), (1, 3)],
set![(0, 2), (3, 5)]
]
);
assert_one_of!(
collect(m.nodes()),
[set![0, 1, 3, 5], set![0, 2, 1, 3], set![0, 2, 3, 5]]
);
}
#[cfg(feature = "stable_graph")]
#[test]
fn is_perfect_in_stable_graph() {
let mut g: StableUnGraph<(), ()> = StableUnGraph::from_edges(&[(0, 1), (1, 2), (2, 3)]);
g.remove_node(NodeIndex::new(0));
g.remove_node(NodeIndex::new(1));
let m = maximum_matching(&g);
assert_eq!(m.len(), 1);
assert!(m.is_perfect());
}
|
