leetcode-algorithms-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
解法
/**
* 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 (l1 == nullptr && l2 == nullptr) return nullptr;
ListNode *head = new ListNode(0);
ListNode *l = head;
while(l1 != nullptr && l2 != nullptr)
{
if (l1->val <= l2->val)
{
l->next = l1;
l1 = l1->next;
}
else
{
l->next = l2;
l2 = l2->next;
}
l = l->next;
}
l->next= l1 ? l1 : l2;
return head->next;
}
};