Skip to content
Map a binary tree to a list.
HTML Common Lisp
Branch: master
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Permalink
Type Name Latest commit message Commit time
Failed to load latest commit information.
.gitignore Add gitignore file. Jul 27, 2019
LICENSE-MIT
README.md
api.html Add generated API documentation. Jul 27, 2019
flat-tree.asd Make into a quicklisp project. Jul 27, 2019
flat-tree.lisp
package.lisp Export its public API. Jul 27, 2019

README.md

flat-tree

Map a binary tree to a list. Common Lisp implementation, adapted from mafintosh/flat-tree.

API

Usage

> (flat-tree:parent 0)
1

Why?

You can represent a binary tree in a simple flat list using the following structure:

      3
  1       5
0   2   4   6  ...

Each number represents an index in a flat list. So a tree:

      A
  B       C
D   E   F   G  ...

would be represented as a list: [D B E A F C G]

Furthermore, indexes 0, 2, 4, 6 are on depth 0. 1, 5, 9 on depth 1. And so forth.

depth = 2  ^        3
depth = 1  |    1       5
depth = 0  |  0   2   4   6  ...

In some cases it is also useful to calculate an offset. Indexes 0, 1, 3, 7 have an offset 0:

                (7)
       (3)
  (1)       5
(0)   2   4   6      ...

2, 5, 11, 23 offset 1:

                 7
       3                  (11)
  1        (5)        9          13
0   (2)   4   6    10   12    14    15

This module exposes a series of functions to help you build and maintain this data structure.

License

MIT

You can’t perform that action at this time.