LC 21. Merge Two Sorted Lists

 1 /**
 2  * Definition for singly-linked list.
 3  * struct ListNode {
 4  *     int val;
 5  *     ListNode *next;
 6  *     ListNode(int x) : val(x), next(NULL) {}
 7  * };
 8  */
 9 class Solution {
10 public:
11     ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
12         ListNode res(0); // content
13         ListNode* cur = &res; // pointer cur = taking addree of res
14         // *content. &pointer->
15         
16         while(l1&&l2){
17             if(l1->val > l2 ->val){
18                 cur->next = l2;
19                 l2 = l2->next;
20             }else{
21                 cur->next = l1;
22                 l1 = l1->next;
23             }
24             cur = cur->next;
25         }
26         cur->next = l2?l2:l1;
27         return res.next;
28     }
29 };