链表常用思路

[lovelmh13]

找链表的中间值

用快慢指针

function findMid (head) {
  let slow = head
  let fast = head
  while (fast.next && fast.next.next) {
    slow = slow.next
    fast = fast.next.next
  }
  const newHead = slow.next // 后半段拆出来
  slow.next = null // 将链表切断，把前半段拆出来
  return newHead // 后半段是 newHead，前半段是 head
}

反转链表

画个图就懂了

function reverseList (head) {
  let initHead = head
  let pre = head

  while (initHead && initHead.next) {
    const node = initHead.next
    initHead.next = initHead.next.next
    node.next = pre
    pre = node
  }
  return pre
}