题目

https://leetcode-cn.com/problems/merge-two-sorted-lists/

解题

  1. /**
  2.  * Definition for singly-linked list.
  3.  * function ListNode(val, next) {
  4.  *     this.val = (val===undefined ? 0 : val)
  5.  *     this.next = (next===undefined ? null : next)
  6.  * }
  7.  */
  8. /**
  9.  * @param {ListNode} l1
  10.  * @param {ListNode} l2
  11.  * @return {ListNode}
  12.  */
  13. var mergeTwoLists = function(l1, l2) {
  14.     if(l1 === null) {
  15.         return l2
  16.     }
  17.     if(l2 === null) {
  18.         return l1
  19.     }
  21. // result
  22.     let head = prev = new ListNode()
  24.     while(l1 !== null && l2 !== null) {
  25.         if (l1.val > l2.val) {
  26.             // 移动指针
  27.             prev.next = l2
  28.             l2 = l2.next
  29.         } else {
  30.             prev.next = l1
  31.             l1 = l1.next
  32.         }
  33.         prev = prev.next
  34.     }
  36.     if(l1 === null) {
  37.         prev.next = l2
  38.     }
  39.     if(l2 === null) {
  40.         prev.next = l1
  41.     }
  43.     return head.next
  45. };