# 21. 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.
Example:
Input: 1->2->4, 1->3->4
Output: 1->1->2->3->4->4
# Solution
Approach 1: Two pointers.
# Code (Python)
Approach 1:
# Code (C++)
Approach 1:
/**
* 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) {
ListNode dummyNode(0);
ListNode *l3 = &dummyNode;
while (l1 && l2)
{
if (l1->val < l2->val)
{
l3->next = l1;
l1 = l1->next;
}
else
{
l3->next = l2;
l2 = l2->next;
}
l3 = l3->next;
}
if (l1)
l3->next = l1;
else if (l2)
l3->next = l2;
return dummyNode.next;
}
};