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binary_search_tree.ts
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225 lines (195 loc) · 5.13 KB
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/**
* Represents a node of a binary search tree.
*
* @template T The type of the value stored in the node.
*/
class TreeNode<T> {
constructor(
public data: T,
public leftChild?: TreeNode<T>,
public rightChild?: TreeNode<T>,
) {}
}
/**
* An implementation of a binary search tree.
*
* A binary tree is a tree with only two children per node. A binary search tree on top sorts the children according
* to following rules:
* - left child < parent node
* - right child > parent node
* - all children on the left side < root node
* - all children on the right side > root node
*
* For profound information about trees
* @see https://www.geeksforgeeks.org/introduction-to-tree-data-structure-and-algorithm-tutorials/
*
* @template T The data type of the values in the binary tree.
*/
export class BinarySearchTree<T> {
rootNode?: TreeNode<T>;
/**
* Instantiates the binary search tree.
*
* @param rootNode The root node.
*/
constructor() {
this.rootNode = undefined;
}
/**
* Checks, if the binary search tree is empty, i. e. has no root node.
*
* @returns Whether the binary search tree is empty.
*/
isEmpty(): boolean {
return this.rootNode === undefined;
}
/**
* Checks whether the tree has the given data or not.
*
* @param data The data to check for.
*/
has(data: T): boolean {
if (!this.rootNode) {
return false;
}
let currentNode = this.rootNode;
while (currentNode.data !== data) {
if (data > currentNode.data) {
if (!currentNode.rightChild) {
return false;
}
currentNode = currentNode.rightChild;
} else {
if (!currentNode.leftChild) {
return false;
}
currentNode = currentNode.leftChild;
}
}
return true;
}
/**
* Inserts the given data into the binary search tree.
*
* @param data The data to be stored in the binary search tree.
* @returns
*/
insert(data: T): void {
if (!this.rootNode) {
this.rootNode = new TreeNode<T>(data);
return;
}
let currentNode: TreeNode<T> = this.rootNode;
while (true) {
if (data > currentNode.data) {
if (currentNode.rightChild) {
currentNode = currentNode.rightChild;
} else {
currentNode.rightChild = new TreeNode<T>(data);
return;
}
} else {
if (currentNode.leftChild) {
currentNode = currentNode.leftChild;
} else {
currentNode.leftChild = new TreeNode<T>(data);
return;
}
}
}
}
/**
* Finds the minimum value of the binary search tree.
*
* @returns The minimum value of the binary search tree
*/
findMin(): T {
if (!this.rootNode) {
throw new Error('Empty tree.');
}
const traverse = (node: TreeNode<T>): T => {
return !node.leftChild ? node.data : traverse(node.leftChild);
};
return traverse(this.rootNode);
}
/**
* Finds the maximum value of the binary search tree.
*
* @returns The maximum value of the binary search tree
*/
findMax(): T {
if (!this.rootNode) {
throw new Error('Empty tree.');
}
const traverse = (node: TreeNode<T>): T => {
return !node.rightChild ? node.data : traverse(node.rightChild);
};
return traverse(this.rootNode);
}
/**
* Traverses to the binary search tree in in-order, i. e. it follow the schema of:
* Left Node -> Root Node -> Right Node
*
* @param array The already found node data for recursive access.
* @returns
*/
inOrderTraversal(array: T[] = []): T[] {
if (!this.rootNode) {
return array;
}
const traverse = (node?: TreeNode<T>, array: T[] = []): T[] => {
if (!node) {
return array;
}
traverse(node.leftChild, array);
array.push(node.data);
traverse(node.rightChild, array);
return array;
};
return traverse(this.rootNode);
}
/**
* Traverses to the binary search tree in pre-order, i. e. it follow the schema of:
* Root Node -> Left Node -> Right Node
*
* @param array The already found node data for recursive access.
* @returns
*/
preOrderTraversal(array: T[] = []): T[] {
if (!this.rootNode) {
return array;
}
const traverse = (node?: TreeNode<T>, array: T[] = []): T[] => {
if (!node) {
return array;
}
array.push(node.data);
traverse(node.leftChild, array);
traverse(node.rightChild, array);
return array;
};
return traverse(this.rootNode);
}
/**
* Traverses to the binary search tree in post-order, i. e. it follow the schema of:
* Left Node -> Right Node -> Root Node
*
* @param array The already found node data for recursive access.
* @returns
*/
postOrderTraversal(array: T[] = []): T[] {
if (!this.rootNode) {
return array;
}
const traverse = (node?: TreeNode<T>, array: T[] = []): T[] => {
if (!node) {
return array;
}
traverse(node.leftChild, array);
traverse(node.rightChild, array);
array.push(node.data);
return array;
};
return traverse(this.rootNode);
}
}