krahets/hello-algo · error · Error

стек пуст

Error message

стек пуст

What it means

Thrown by LinkedListStack.peek (JS) with message 'стек пуст' when #stackPeek is null (no nodes). pop() calls peek() first, so the throw also surfaces from pop() on an empty stack.

Source

Thrown at ru/codes/javascript/chapter_stack_and_queue/linkedlist_stack.js:46

    /* Поместить в стек */
    push(num) {
        const node = new ListNode(num);
        node.next = this.#stackPeek;
        this.#stackPeek = node;
        this.#stkSize++;
    }

    /* Извлечь из стека */
    pop() {
        const num = this.peek();
        this.#stackPeek = this.#stackPeek.next;
        this.#stkSize--;
        return num;
    }

    /* Доступ к верхнему элементу стека */
    peek() {
        if (!this.#stackPeek) throw new Error('стек пуст');
        return this.#stackPeek.val;
    }

    /* Преобразовать связный список в Array и вернуть */
    toArray() {
        let node = this.#stackPeek;
        const res = new Array(this.size);
        for (let i = res.length - 1; i >= 0; i--) {
            res[i] = node.val;
            node = node.next;
        }
        return res;
    }
}

/* Driver Code */
/* Инициализация стека */
const stack = new LinkedListStack();

View on GitHub (pinned to 69932aed18)

Solutions

1. Guard on isEmpty()/size before peek or pop.
2. Treat empty-on-pop as a domain-level 'unbalanced' signal rather than a crash.
3. Maintain an explicit size invariant alongside the head pointer.

Example fix

// before
const v = stack.peek(); // throws when empty

// after
const v = stack.isEmpty() ? null : stack.peek();

const v = stack.isEmpty() ? null : stack.pop();

try { stack.peek(); } catch (e) { if (e.message !== 'стек пуст') throw e; }

When it happens

Trigger: Calling peek() or pop() when #stackPeek === null, i.e., the linked list is empty (#stkSize === 0).

Common situations: Over-popping a linked-list-backed stack; DFS/recursion simulation that pops more than it pushes; bracket matching closing with an empty stack.

Related errors

• стек пуст
• очередь пуста
• 堆疊為空
• 栈为空
• Stack is empty

AI-assisted analysis of krahets/hello-algo@69932aed18 (2026-08-13). Data as JSON: /api/errors/37f8462b2542c6e5. Report an issue: GitHub.