Deque.ts
For the full content of this gist, refer to https://gist.github.com/CodingAbdullah/cefc05e0ca09a3c5fa5a6b90d901a8a5
McMaster. Software Engineer with a keen interest in blockchain and web3.
import { LinkedList } from '../LinkedLists/LinkedList';
// Double-Ended Queue that implements a Queue at both ends of a list
// We can append at the front and the back, remove at the front and the back
// FIFO at the front and FIFO at the back
class Deque {
dequeList: LinkedList;
// Initialize the double-ended queue
constructor() {
this.dequeList = new LinkedList();
}
// Peek at the front of the deque
peekFront(): number | null {
if (this.dequeList.length() === 0) {
return null;
}
else {
// Check the head of the list
// Return the value of the item
let headNode = this.dequeList.head;
return headNode!.item;
}
}
// Peek at the end of the deque
peekLast(): number | null {
if (this.dequeList.length() === 0) {
return null;
}
else {
let headItem = this.dequeList.head;
// Traverse to the end of the Deque
while (headItem!.next !== null) {
headItem = headItem!.next;
}
return headItem!.item
}
}
// Append item at the front of the deque
frontEnqueue(item: number): void {
this.dequeList.appendFirst(item);
}
// Append item at the back of the deque
backEnqueue(item: number): void {
this.dequeList.appendLast(item);
}
// Remove item at the front of the deque
frontDequeue(): number | null {
return this.dequeList.removeFirst();
}
// Remove item from the back of the deque
backDequeue(): number | null {
return this.dequeList.removeLast();
}
// Return the length of the double-ended Queue
length(): number {
return this.dequeList.length();
}
}
export { Deque };