class Solution {
public:
ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
if(l1 == nullptr) return l2;
if(l2 == nullptr) return l1;
ListNode* newHead = nullptr, *newEnd = nullptr;
ListNode* getNode = nullptr;
while(l1 && l2){
getNode = l1->val < l2->val?l1:l2;
getNode == l1?l1 = l1->next:l2 = l2->next;
!newHead?newHead = newEnd = getNode:newEnd=newEnd->next = getNode;
}
while(l1){
newEnd = newEnd->next = l1;
l1 = l1->next;
}
while(l2){
newEnd = newEnd->next = l2;
l2 = l2->next;
}
return newHead;
}
};