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import { StackType, DataType, StackApi, StackNode } from "./helper.ts"
export class Stack implements StackApi {	private topNode: StackType	private bottomNode: StackType	public size: number
	constructor() {		this.topNode = null		this.bottomNode = null		this.size = 0	}
	getTop() {		if (this.topNode === null) return null;		return this.topNode!.data	}
	getBottom() {		if (this.topNode === null) return null;		return this.bottomNode!.data	}
	push(data: DataType<any>) {		const newNode = new StackNode(data)		if (this.topNode === null) {			this.topNode = newNode			this.bottomNode = newNode			return true;		}				newNode.next = this.topNode		if (newNode.next === null) {			this.bottomNode = newNode.next		}		this.topNode = newNode		this.size++
		return true;	}
	pop() {		if (this.topNode === null) {			return false;		} else if (this.topNode!.next === null) {			this.bottomNode = null		}				const node = this.topNode		this.topNode = node!.next		this.size--		if (this.topNode === null) this.size = 0
		return node!.data;	}
	search(key: string|number) {		if (this.topNode === null) {			return null		}
		if (key === this.topNode!.data.key) {			return this.topNode!.data		}		if (key === this.bottomNode!.data.key) {			return this.bottomNode!.data		}
		let currentNode = this.topNode!.next		while (currentNode !== null) {			if (key === currentNode.data.key) {				return currentNode.data			}			currentNode = currentNode.next		}
		return null	}
	update(key: string|number, newValue: any) {		if (this.topNode === null) {			return false		}
		if (key === this.topNode!.data.key) {			this.topNode!.data.value = newValue			return this.topNode!.data		}		if (key === this.bottomNode!.data.key) {			this.bottomNode!.data.value = newValue			return this.bottomNode!.data		}
		let currentNode: StackType = this.topNode		while (currentNode !== null) {			if (key === currentNode.data.key) {				currentNode.data.value = newValue				return currentNode.data			}
			currentNode = currentNode.next		}
		return false	}}