https://github.com/mikolalysenko/inorder-tree-layout

Index calculations for balanced binary search trees in in-order layout
https://github.com/mikolalysenko/inorder-tree-layout

Last synced: about 2 months ago
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Index calculations for balanced binary search trees in in-order layout

• Host: GitHub
• URL: https://github.com/mikolalysenko/inorder-tree-layout
• Owner: mikolalysenko
• License: mit
• Created: 2013-04-11T16:12:31.000Z (over 11 years ago)
• Default Branch: master
• Last Pushed: 2014-04-28T23:49:27.000Z (over 10 years ago)
• Last Synced: 2024-10-20T14:28:21.221Z (2 months ago)
• Language: JavaScript
• Size: 172 KB
• Stars: 9
• Watchers: 3
• Forks: 5
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
inorder-tree-layout

===================

Operations on nodes for balanced binary trees stored in in-order layout.  These are useful if you are building data structures, like binary search trees, implicitly (ie not storing pointers to subtrees).

## Install

    npm install inorder-tree-layout

    

## Example

Suppose we have a tree with 10 elements, packed in level order.  Then the inorder labelling of this tree looks like the following picture:

```

The tree:

          6

        /   \

       3     8

      / \   / \

     1   5 7   9

    / \  |

   0   2 4

```

Now given this tree, here is how we can compute some queries using this library:

```javascript

var layout = require("inorder-tree-layout")

console.log(layout.left(10, 3))     //Prints:  1

console.log(layout.parent(10, 7))   //Prints:  8

console.log(layout.height(10, 9))   //Prints:  0

```

## API

```javascript

var layout = require("inorder-tree-layout")

```

**Conventions:**

* `n` is always the size of the tree

* `x` is the index of a node in the tree

### `layout.root(n)`

Returns the index of the root of a tree of size n.

### `layout.begin(n)`

Returns the index of the first node of the tree

### `layout.end(n)`

Returns the index of the last node in the tree

### `layout.height(n, x)`

Returns the height of node `x` in a tree of size `n`

### `layout.prev(n, x)`

Returns the predecessor of `x` in an in-order traversal

### `layout.next(n, x)`

Returns the successor of `x` in an in-order traversal

### `layout.parent(n, x)`

Returns the parent of `x` in a tree of size `n`

### `layout.left(n, x)`

Returns the left child of `x`

### `layout.right(n, x)`

Returns the right child of `x`

### `layout.leaf(n, x)`

Returns true if `x` is a leaf node.

### `layout.lo(n, x)`

Returns the left most ancestor of `x` in the tree

### `layout.hi(n, x)`

Returns the right most ancestor of `x` in the tree

# Credits

(c) 2013 Mikola Lysenko. MIT License