#Leetcode# 21. Merge Two Sorted Lists

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

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

代码：

/**
 * 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 *dummy = new ListNode(-1), *cur = dummy;
        while(l1 && l2) {
            if(l1 -> val < l2 -> val) {
                cur -> next = l1;
                l1 = l1 -> next;
            } else {
                cur -> next = l2;
                l2 = l2 -> next;
            }
            cur = cur -> next;
        }
        cur -> next = l1 ? l1 : l2;
        return dummy -> next;
    }
};