Priority Queue presented by Easy LeetCode

class PQ<T> {
  head: PriorityQueueNode<T> | null = null;

  get empty() {
    return this.head === null;
  }

  insert(value: T, priority: number) {
    const node: PriorityQueueNode<T> = { value, priority, next: null };
    if (!this.head) {
      this.head = node;
      return;
    }

    if (this.head.priority < node.priority) {
      node.next = this.head;
      this.head = node;
      return;
    }

    let cursor = this.head;

    while (cursor.next && cursor.next.priority > node.priority) {
      cursor = cursor.next;
    }

    const oldNext = cursor.next;
    cursor.next = node;
    node.next = oldNext;
  }

  shift(): T | undefined {
    if (this.head) {
      const oldHead = this.head;
      this.head = oldHead.next;
      oldHead.next = null;

      return oldHead.value;
    }
  }
}

interface PriorityQueueNode<T> {
  priority: number;
  value: T;
  next: PriorityQueueNode<T> | null;
}

Use Priority Queue on LeetCode

Copy this snippet and paste it to the bottom of your LeetCode editor so that you can use the Priority Queue.

Don’t use it where the problem itself is to implement a Priority Queue.