LeetCode Merge Two Sorted Lists

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.

入门题目了，严蔚敏的书本好像一开始就介绍了这样的题目，以前死背了好多次，始终背不出来，现在已经不用背了，感觉随时都能写出不比书本差的程序。

本题就是考链表的操作了。

链表的操作是要练出感觉来的。

下面的程序提供到位操作，把链表2直接插入链表1中。

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     ListNode *next;
*     ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
if (!l2) return l1;
if (!l1) return l2;

ListNode *h = l1;

if (l1->val > l2->val)
{
ListNode *t = l2->next;
l2->next = l1;
h = l1 = l2;
l2 = t;
}

while (l1->next && l2)
{
if (l1->next->val > l2->val)
{
ListNode *t = l2->next;
l2->next = l1->next;
l1->next = l2;
l2 = t;
}
l1 = l1->next;
}

if (l2) l1->next = l2;

return h;
}
};