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The example & the code looks incorrect; a simpler solution exists

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#1

The second example with k=8 looks incorrect.

Let’s rotate the list for 8 iterations manually:

1 → 2 → 3 → 4 → 5

  1. 2 → 3 → 4 → 5 → 1
  2. 3 → 4 → 5 → 1 → 2
  3. 4 → 5 → 1 → 2 → 3
  4. 5 → 1 → 2 → 3 → 4
  5. 1 → 2 → 3 → 4 → 5
  6. 2 → 3 → 4 → 5 → 1
  7. 3 → 4 → 5 → 1 → 2
  8. 4 → 5 → 1 → 2 → 3

So finally we got 4 → 5 → 1 → 2 → 3, not 3 → 4 → 5 → 1 → 2 as the article states.

To achieve that, why can’t we just:

  1. Find the tail of the list

  2. Move the nodes one by one from the head to the tail of the list, updating the counter?

    const rotate = function (head, rotations) {
    if (!head || !head.next) return head;

    let tail = head;

    while (tail.next) {
    tail = tail.next;
    }

    for (let i = 0; i < rotations; i++) {
    tail.next = head;
    tail = head;
    head = head.next;
    tail.next = null;
    }

    return head;
    };

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Course: https://www.educative.io/collection/5668639101419520/5671464854355968
Lesson: https://www.educative.io/collection/page/5668639101419520/5671464854355968/5497500834201600

#2

Hi there,
You are rotating from the left side, but the example given in the lesson is rotating from the right.
The example and code given in the lesson are correct both.