2 releases
Uses old Rust 2015
0.1.1 | Jul 26, 2018 |
---|---|
0.1.0 | Jul 22, 2018 |
#2366 in Data structures
20KB
459 lines
LOUDS
This crate provides a succinct data structure called LOUDS (level order unary degree sequence). LOUDS represents an ordered tree structure and supports almost constant-time tree traversal operations.
In LOUDS, a tree structure containing n nodes is repsresented as a bit sequence of length 2n + 1. We compress the sequence by using fid.
This crate also includes Trie implementation with LOUDS.
Usage
Add this to your Cargo.toml
.
[dependencies]
louds = "0.1.1"
Examples
Ordered Tree
0
/ \
1 2
/ | \ / \
3 4 5 6 7
/ \ | |
8 9 10 11
extern crate louds;
use louds::Louds;
// Create LOUDS tree by pushing degree (# of children) of
// each node in breadth-first order.
let degrees = &[ 2, 3, 2, 0, 2, 1, 1, 0, 0, 0, 0, 0 ];
let mut louds = Louds::new();
for &d in degrees {
louds.push_node(d);
}
// Tree traversal operations (move to parent/children/sibling)
// are supported in constant-time.
assert_eq!(louds.first_child(1), Some(3));
assert_eq!(louds.first_child(3), None);
assert_eq!(louds.last_child(2), Some(7));
assert_eq!(louds.last_child(7), None);
assert_eq!(louds.child(1, 1), Some(4));
assert_eq!(louds.parent(4), Some(1));
assert_eq!(louds.sibling(4), Some(5));
assert_eq!(louds.degree(4), 2);
// Computing depth of a node takes time proportional to
// the height of the tree.
assert_eq!(louds.depth(4), 2);
Credits
LOUDS representation was first proposed in [1].
[1] G. Jacobson(1989). Space-efficient Static Trees and Graphs. In Proc. IEEE FOCS, pages 549–554.
[2] 定兼 邦彦(2018). 簡潔データ構造. 共立出版.
Dependencies
~0.4–1MB
~23K SLoC