AVL Tree

This package implements a basic AVL Tree. Basic means node payloads are scalar and comparable with built-in operators <, <=, >, >=. The current implementation supports insert only. There is no validation that inputs match previous types.

There is, however, tests for full code coverage and basic metrics for tree operations.

Usage

const Tree = require('avl-tree');
let tree = new Tree();
tree.add('a');
tree.add('b');
tree.add('f');  // causes a left rotation
tree.add('c');
tree.add('d');  // causes a double rotation R balance
tree.toArray(); // outputs tree in 'infix' order, by default
tree.toArray({notation: 'postfix'}); // output in postfix order
tree.toArray({notation: 'prefix'});  // output in prefix order

Statistics

Basic metrics are available. Calling tree.metrics() return a JSON object with aggregated statistics for the entire tree:

• add - Number of times a new value is added to any part of the tree.
• insertion - Number of times a new value is added to the entire tree. Should match the number of values added to the tree by tree.add().
• leftRotation / rightRotation - Number of times a left- or right-rotation took place.
• leftBalance / rightBalance - Number of times the tree violated AVL constraints and required the left- or right side to be balanced.

I have plans to extend the general usefulness of this module and I welcome all suggestions!