@datastructures-js/binary-search-tree

Binary Search Tree & AVL Tree (Self Balancing Tree) implementation in javascript.

Binary Search Tree
AVL Tree (Self Balancing Tree)

Table of Contents

• Install
• API
  • require
  • import
  • new
  • .insert(key, value)
  • .has(key)
  • .find(key)
  • .min()
  • .max()
  • .lowerBound(k)
  • .upperBound(k)
  • .root()
  • .count()
  • .traverseInOrder(cb)
  • .traversePreOrder(cb)
  • .traversePostOrder(cb)
  • .remove(key)
  • .clear()
  • BinarySearchTreeNode
  • AvlTreeNode
• Build
• License

install

npm install --save @datastructures-js/binary-search-tree

API

require

const {
  BinarySearchTree,
  BinarySearchTreeNode,
  AvlTree,
  AvlTreeNode
} = require('@datastructures-js/binary-search-tree');

import

import {
  BinarySearchTree,
  BinarySearchTreeNode,
  AvlTree,
  AvlTreeNode
} from '@datastructures-js/binary-search-tree';

new

const bst = new BinarySearchTree();

// self balancing tree
const bst = new AvlTree();

.insert(key, value)

inserts a node with key/value into the tree and returns the inserted node. Inserting an node with existing key, will update the existing node's value with the new one.

bst.insert(50, 'v1');
bst.insert(80, 'v2');
bst.insert(30, 'v3');
bst.insert(90, 'v4');
bst.insert(60, 'v5');
bst.insert(40, 'v6');
bst.insert(20, 'v7');

.has(key)

checks if a node exists by its key.

bst.has(50); // true
bst.has(100); // false

.find(key)

finds a node in the tree by its key.

const n60 = bst.find(60);
console.log(n60.getKey()); // 60
console.log(n60.getValue()); // v5

console.log(bst.find(100)); // null

.min()

finds the node with min key in the tree.

const min = bst.min();
console.log(min.getKey()); // 20
console.log(min.getValue()); // v7

.max()

finds the node with max key in the tree.

const max = bst.max();
console.log(max.getKey()); // 90
console.log(max.getValue()); // v4

.lowerBound(k)

finds the node with the biggest key less or equal a given value k.

console.log(bst.lowerBound(60).getKey()); // 50
console.log(bst.lowerBound(10)); // null

.upperBound(k)

finds the node with the smallest key bigger than a given value k.

console.log(bst.upperBound(75).getKey()); // 80
console.log(bst.upperBound(110)); // null

.root()

returns the root node of the tree.

const root = bst.root();
console.log(root.getKey()); // 50
console.log(root.getValue()); // v1

.count()

returns the count of nodes in the tree.

console.log(bst.count()); // 7

.traverseInOrder(cb)

traverses the tree in order (left-node-right).

bst.traverseInOrder((node) => console.log(node.getKey()));

/*
  20
  30
  40
  50
  60
  80
  90
*/

.traversePreOrder(cb)

traverses the tree pre order (node-left-right).

bst.traversePreOrder((node) => console.log(node.getKey()));

/*
  50
  30
  20
  40
  80
  60
  90
*/

.traversePostOrder(cb)

traverses the tree post order (left-right-node).

bst.traversePostOrder((node) => console.log(node.getKey()));

/*
  20
  40
  30
  60
  90
  80
  50
*/

.remove(key)

removes a node from the tree by its key. AVL tree will rotate nodes properly if the tree becomes unbalanced during deletion.

bst.remove(20); // true
bst.remove(100); // false
console.log(bst.count()); // 6

.clear()

clears the tree.

bst.clear();
console.log(bst.count()); // 0
console.log(bst.root()); // null

BinarySearchTreeNode

.getKey()

.setValue(value)

.getValue()

.setLeft(left)

.getLeft()

.hasLeft()

.setRight(right)

.getRight()

.hasRight()

.setParent(parent)

.getParent()

.hasParent()

.isLeaf()

.isRoot()

AvlTreeNode

extends BinarySearchTreeNode and adds the following methods:

.rotateLeft()

Rotates self left (counter-clockwise).

.rotateRight()

Rotates self right (clockwise).

.rotateLeftRight()

Rotates left child to left then self to right.

.rotateRightLeft()

Rotates right child to right then self to left.

.getHeight()

Gets the height of the node in the tree. root height is 1.

.getLeftHeight()

Gets the height of left child. 0 if no left child.

.getRightHeight()

Gets the height of right child. 0 if no right child.

.getBalance()

returns the node's balance as the diff between left and right heights.

.isBalanced()

checks if the node is balanced. (height diff is not more/less than 1/-1)

Build

grunt build

License

The MIT License. Full License is here