61. 旋转链表

61. 旋转链表

代码

javascript

// 61. 旋转链表：https://leetcode.cn/problems/rotate-list/description/
// 输入：head = [1,2,3,4,5], k = 2
// 输出：[4,5,1,2,3]

export function rotateList (head, k) {
  if (k === 0 || !head || !head.next) return head

  let n = 1
  let cur = head
  while (cur.next) {
    cur = cur.next
    n++
  }

  let add = n - k % n
  if (add === n) return head

  cur.next = head
  while (add) {
    cur = cur.next
    add--
  }

  const res = cur.next
  cur.next = null
  return res
}

typescript

// 61. 旋转链表：https://leetcode.cn/problems/rotate-list/description/
// 输入：head = [1,2,3,4,5], k = 2
// 输出：[4,5,1,2,3]

import { type ListNode } from "../../utils"

export function rotateList (head: ListNode | null, k: number): ListNode | null {
  if (k === 0 || !head || !head.next) return head

  let n = 1
  let cur = head
  while (cur.next) {
    cur = cur.next
    n++
  }

  let add = n - k % n
  if (add === n) return head

  cur.next = head
  while (add) {
    cur = cur.next as ListNode
    add--
  }

  const res = cur.next
  cur.next = null
  return res
}