1.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
2.题目要求：合并两个排序好的链表。
3.方法：遍历两个链表，每次取最小值。
4.代码：
class Solution {
public:
ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
ListNode * head = new ListNode(0);
ListNode * ptr = head;
while(l1 != NULL || l2 != NULL){
ListNode * cur = NULL;
if(l1 == NULL){
cur = l2;
l2 = l2->next;
}
else if(l2 == NULL){
cur = l1;
l1 = l1->next;
}
else{
if(l1->val < l2->val){
cur = l1;
l1 = l1->next;
}
else{
cur = l2;
l2 = l2->next;
}
}
ptr->next = cur;
ptr = ptr->next;
}
return head->next;
}
};
