算法分析与设计课程——LeetCode刷题之Merge Two Sorted Lists

题目：

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

答案：
class Solution {
public:
ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
ListNode dummy(INT_MIN);
ListNode *tail = &dummy;

while (l1 && l2) {
if (l1->val < l2->val) {
tail->next = l1;
l1 = l1->next;
} else {
tail->next = l2;
l2 = l2->next;
}
tail = tail->next;
}

tail->next = l1 ? l1 : l2;
return dummy.next;
}
};