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) { // Start typing your C/C++ solution below // DO NOT write int main() function ListNode* root; ListNode* tail; if(l1!=NULL&&l2!=NULL){ if(l1->val>l2->val){ root=l2; tail=root; l2=l2->next; } else{ root=l1; tail=root; l1=l1->next; } while(l1!=NULL&&l2!=NULL){ if(l1->val>l2->val){ tail->next=l2; tail=tail->next; l2=l2->next; } else{ tail->next=l1; tail=tail->next; l1=l1->next; } } if(l1!=NULL)tail->next=l1; if(l2!=NULL)tail->next=l2; return root; } else{ if(l2==NULL)return l1; else return l2; } } };