btree

A rebalancing binary tree for JS

To install / use:
``shell
npm install btree-js
`

#### Basic Usage
`javascript
var BinaryTree = require('btree-js');
var Tree = BinaryTree.Tree;
var Node = BinaryTree.Node;

var tree = new Tree();
tree.insert(new Node({ key: 10, text: 'blah' })); // becomes tree's root
tree.insert(new Node({ key: 15, text: 'plop' })); // tree.root.right.key: 15
`

$3

##### key
The binary tree defaults to key property unless a key is explicitly passed in.

`javascript
var tree = new Tree({ key: 'id' });
tree.insert(1);
console.log(tree.root.id); // 1
`

##### unique
The binary tree defaults to allowing multiple identical keys. If unique: true is passed in as an option, it will throw an error when inserting a duplicate key.

`javascript
var tree = new Tree({ unique: true });
tree.bulkInsert(1, 1); // throws duplicate key violation
`

$3

#### isEmpty
Returns whether or not the tree has nodes in it.
`javascript
var tree = new Tree();
console.log(tree.isEmpty()); // true

tree.insert(new Node({ key: 6 });
console.log(tree.isEmpty()); // false

tree.delete(6);
console.log(tree.isEmpty()); // true
`

#### delete
Allows you to pass in either a node or a key to delete that node from the tree. If the tree becomes unbalanced as a result, it will rebalance itself.

`javascript
tree.bulkInsert(5, 3, 10, 8);
tree.print();

5

3 10

8

tree.delete(3);
tree.print();

8

5 10
`

#### min
Returns the minimum key in the tree. If a node is provided, it will find the minimum key in that subtree.

`javascript
tree.bulkInsert(50, 25, 90, 180, 40);
console.log(tree.min().key); // 25

tree.delete(tree.min());
console.log(tree.min().key); // 40
`

#### max
Returns the maximum key in the tree. If a node is provided, it will find the maximum key in that subtree.

`javascript
tree.bulkInsert(50, 25, 90, 180, 40);
console.log(tree.max().key); // 180

tree.delete(tree.max());
console.log(tree.max().key); // 90
`

#### search
Returns a node with the given key, if found. Otherwise, returns null.
`javascript
tree.insert(new Node({ key: 10, text: 'blah' }));
tree.insert(new Node({ key: 15, text: 'plop' }));

var node = tree.search(15);
console.log(node.text); // plop
console.log(node.parent.key); // 10
`

#### findPaths
Returns a list of paths from the root to the leaf (array of array of nodes).

`javascript
tree.bulkInsert(2, 1, 3);
var paths = tree.findPaths();
paths.forEach(function path) {
var keys = path.map(function (node) { return node.key; });
console.log(keys.join(' '));
});

// 2 1
// 2 3
`

#### height
Returns the height of the tree. With n nodes, the height of the
tree will be approximately log(n).
`javascript
var tree = new Tree();
tree.bulkInsert(10, 5, 15, 2, 7, 12, 18);
tree.height(); // 3
`

#### invert
Inverts the tree by taking all the node pointers and flipping them.

`javascript
tree.bulkInsert(50, 25, 75, 60, 90);
tree.print();

50

25 75

60 90

tree.invert();
tree.print();

90

25 50

60 75
`

#### print
To print a text-view of the tree,

`javascript
tree.print();

7

3 13

1 5 9 17

2 4 6 8 11 15 18

14 19
`

#### inOrderTraversal
An iterator that returns the nodes via:

1. Return node from left tree (recursive)
2. Return self
3. Return node from right tree (recursive)

`javascript
tree.inOrderTraversal(function (node) {
console.log(node.value);
});
`


#### preOrderTraversal
An iterator that returns the nodes via:

1. Return self
2. Return node from left tree (recursive)
3. Return node from right tree (recursive)

`javascript
tree.preOrderTraversal(function (node) {
console.log(node.value);
});
`


#### postOrderTraversal
An iterator that returns the nodes via:

1. Return node from left tree (recursive)
2. Return node from right tree (recursive)
3. Return self

`javascript
tree.postOrderTraversal(function (node) {
console.log(node.value);
});
``


Written by JT Bowler, 2016.