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.

struct ListNode {int val;    ListNode *next;    ListNode(int x) : val(x), next(NULL) {} };ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {ListNode *helper=new ListNode(0);ListNode *head=helper;while(l1 && l2){if(l1->val< l2->val){helper->next=l1;l1=l1->next;}else{helper->next=l2;l2=l2->next;}helper=helper->next;}if(l1)helper->next=l1;if(l2)helper->next=l2;return head->next;}