LouisTsang-jk.github.io

链表的中间结点

出处

leetcode｜链表的中间结点

题解/思路

快慢指针

快指针比慢指针运动快一倍

• 空间复杂度 O(1)

• 时间复杂度 O(n)

  /**
  * Definition for singly-linked list.
  * function ListNode(val, next) {
  *     this.val = (val===undefined ? 0 : val)
  *     this.next = (next===undefined ? null : next)
  * }
  */
  /**
  * @param {ListNode} head
  * @return {ListNode}
  */
  var middleNode = function(head) {
  let slow = head;
  let fast = head;
  while (fast && fast.next) {
    slow = slow.next;
    fast = fast.next.next;
  }
  return slow;
  };