1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
use crate::algo::graph::tree::center::{Center, TreeCenter};
use crate::algo::graph::tree::rooting::TreeNode;
use crate::algo::graph::UnweightedAdjacencyList;
impl From<Center> for Vec<usize> {
fn from(center: Center) -> Self {
match center {
Center::One(x) => vec![x],
Center::Two(x, y) => vec![x, y],
}
}
}
impl TreeNode {
pub fn encode(&self) -> Vec<u8> {
let mut labels: Vec<_> = self.children.iter().map(|node| node.encode()).collect();
labels.sort();
let mut res = Vec::new();
res.push(b'(');
for label in &labels {
res.extend_from_slice(label);
}
res.push(b')');
res
}
}
impl UnweightedAdjacencyList {
pub fn is_isomorphic_with(&self, other: &UnweightedAdjacencyList) -> bool {
let this_centers: Vec<usize> = self.center().into();
let other_centers: Vec<usize> = other.center().into();
for &c1 in &this_centers {
let tree1 = TreeNode::from_adjacency_list(&self, c1);
for &c2 in &other_centers {
let tree2 = TreeNode::from_adjacency_list(&self, c2);
if tree1.encode() == tree2.encode() {
return true;
}
}
}
false
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_tree_encoding() {
let mut adj = UnweightedAdjacencyList::with_size(10);
adj.add_undirected_edge(0, 2);
adj.add_undirected_edge(0, 1);
adj.add_undirected_edge(0, 3);
adj.add_undirected_edge(2, 6);
adj.add_undirected_edge(2, 7);
adj.add_undirected_edge(1, 4);
adj.add_undirected_edge(1, 5);
adj.add_undirected_edge(5, 9);
adj.add_undirected_edge(3, 8);
let tree = TreeNode::from_adjacency_list(&adj, 0);
let encoded = tree.encode();
let encoded = String::from_utf8(encoded).unwrap();
assert_eq!(&encoded, "(((())())(()())(()))")
}
#[test]
fn test_tree_isomorphism() {
let mut tree1 = UnweightedAdjacencyList::with_size(5);
tree1.add_undirected_edge(2, 0);
tree1.add_undirected_edge(3, 4);
tree1.add_undirected_edge(2, 1);
tree1.add_undirected_edge(2, 3);
let mut tree2 = UnweightedAdjacencyList::with_size(5);
tree2.add_undirected_edge(1, 0);
tree2.add_undirected_edge(2, 4);
tree2.add_undirected_edge(1, 3);
tree2.add_undirected_edge(1, 2);
assert!(tree1.is_isomorphic_with(&tree2));
}
}