Code Review (Easy): Batch Reorder Update

Story

Lena was tasked with refining how the internal task runner handles batches of incoming requests to improve the dashboard's display. Eva noticed that the default sequence wasn't quite right for the new workflow, so she asked Lena to flip the order of items within each group while leaving any leftover items at the end of the line untouched. For example, if there are five requests and the group size is set to three, the first three should be completely reversed while the remaining two stay exactly as they were. This update ensures that small clusters of work are handled in the specific priority order the team requires.

Your Task

Read the story and code, then decide if the code is ready for production or needs improvement.

Hints

What would block an approval? Give me a hint.

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class ListNode {
  val: number;
  next: ListNode | null;
  constructor(val?: number, next?: ListNode | null) {
    this.val = val === undefined ? 0 : val;
    this.next = next === undefined ? null : next;
  }
}

function reverseKGroup(head: ListNode | null, k: number): ListNode | null {
  const dummy = new ListNode(0, head);

function getKth(node: ListNode | null, k: number): ListNode | null {
    let curr = node;
    for (let i = 0; i < k && curr !== null; i++) {
      curr = curr.next;
    }
    return curr;
  }

let groupPrev: ListNode | null = dummy;

while (true) {
    const kth = getKth(groupPrev, k);
    if (kth === null) break;

const groupStart = groupPrev!.next as ListNode;
    const nextGroupStart = kth.next;

// reverse group
    let prev: ListNode | null = nextGroupStart;
    let curr: ListNode | null = groupStart;
    while (curr !== nextGroupStart) {
      const tmp = curr!.next;
      curr!.next = prev;
      prev = curr;
      curr = tmp;
    }

// connect reversed group
    groupPrev!.next = kth;
    groupPrev = groupStart;
  }

return dummy.next;
}