krahets/hello-algo · error · Error

очередь пуста

Error message

очередь пуста

What it means

Thrown by pop() on a linked-list queue when this.front is null/undefined. The message ('очередь пуста') guards the head-node reassignment this.front = this.front.next. Note peek() is called first and already throws on an empty queue, so this redundant guard is a secondary defense.

Source

Thrown at ru/codes/typescript/chapter_stack_and_queue/linkedlist_queue.ts:49

    push(num: number): void {
        // Добавить num после хвостового узла
        const node = new ListNode(num);
        // Если очередь пуста, сделать так, чтобы и head, и tail указывали на этот узел
        if (!this.front) {
            this.front = node;
            this.rear = node;
            // Если очередь не пуста, добавить этот узел после хвостового узла
        } else {
            this.rear!.next = node;
            this.rear = node;
        }
        this.queSize++;
    }

    /* Извлечь из очереди */
    pop(): number {
        const num = this.peek();
        if (!this.front) throw new Error('очередь пуста');
        // Удалить головной узел
        this.front = this.front.next;
        this.queSize--;
        return num;
    }

    /* Доступ к элементу в начале очереди */
    peek(): number {
        if (this.size === 0) throw new Error('очередь пуста');
        return this.front!.val;
    }

    /* Преобразовать связный список в Array и вернуть */
    toArray(): number[] {
        let node = this.front;
        const res = new Array<number>(this.size);
        for (let i = 0; i < res.length; i++) {
            res[i] = node!.val;

View on GitHub (pinned to 69932aed18)

Solutions

1. Check queue.isEmpty() (or queue.size === 0) before pop().
2. Drive consumption with while (!queue.isEmpty()).
3. Catch the error when an empty dequeue is a recoverable signal.
4. Ensure enqueue calls precede dequeue calls in the control flow.

Example fix

// before
const x = queue.pop(); // throws when front is null

// after
const x = queue.isEmpty() ? null : queue.pop();

if (!queue.isEmpty()) {
    const val = queue.pop();
}

try {
    const val = queue.pop();
} catch (e) {
    if (e instanceof Error && e.message === 'очередь пуста') {
        // queue empty; handle gracefully
    } else throw e;
}

When it happens

Trigger: Calling pop() on a queue whose front pointer is null (no elements enqueued or all dequeued); a producer/consumer where the consumer dequeues more than was enqueued.

Common situations: BFS where the queue is drained and then popped once more; resetting a queue and forgetting to reset downstream consumers; concurrent/async producers where the consumer races ahead.

Related errors

• 队列为空
• 队列为空
• 栈为空
• Queue is empty
• Queue is empty

AI-assisted analysis of krahets/hello-algo@69932aed18 (2026-08-13). Data as JSON: /api/errors/8787689e390903a7. Report an issue: GitHub.