learn_example/Structure_LinkedList/LinkedList_Queue.ts

interface LinkedList {
  value: number | null;
  next: LinkedList | null;
}

class LinkedListQueue {
  private head: LinkedList | null = null;
  private tail: LinkedList | null = null;

  private len: number = 0;

  add(value: number) {
    if (this.len === 0) {
      this.head = { value, next: null };
      this.tail = this.head;
      this.len++;
      return;
    }

    this.tail!.next = { value, next: null };
    this.tail = this.tail!.next;
    this.len++;
  }

  pop(): number | null {
    if (!this.head || !this.tail) return null;

    const popValue = this.head.value;
    this.head = this.head.next;
    this.len--;

    return popValue;
  }

  get length() {
    return this.len;
  }

  get link() {
    return this.head;
  }
}