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LeetCode --- 21. Merge Two Sorted Lists

2024-11-24 00:30:39   203人阅读

题目链接：Merge Two Sorted Lists

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

这道题的要求是将两个已经排好序的链表合并成1个有序链表。

这道题的思路比较简单，主要就是考察链表的处理。这里还是像Remove Nth Node From End of List一样先在链表前面加头，这样可以免去对链表头的特殊处理。接下来就是每次取两个链表前面较小的元素，直到有链表到达结尾。最后再将没有到达结尾的链表直接链接到合并的链表的后面，并返回合并后链表头后面的节点指针即可。

时间复杂度：O(n)

空间复杂度：O(1)

 1 class Solution
 2 {
 3 public:
 4     ListNode *mergeTwoLists(ListNode *l1, ListNode *l2)
 5     {
 6         ListNode *h = new ListNode(0), *p = h;
 7         
 8         while(l1 != NULL && l2 != NULL)
 9         {
10             if(l1 -> val < l2 -> val)
11             {
12                 p -> next = l1;
13                 l1 = l1 -> next;
14             }
15             else
16             {
17                 p -> next = l2;
18                 l2 = l2 -> next;
19             }
20             
21             p = p -> next;
22         }
23         
24         if(l1 != NULL)
25             p -> next = l1;
26         if(l2 != NULL)
27             p -> next = l2;
28         
29         return h -> next;
30     }
31 };

转载请说明出处：LeetCode --- 21. Merge Two Sorted Lists

LeetCode --- 21. Merge Two Sorted Lists


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