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.
/**
* 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(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;
}
};