21. 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.
/** * Definition for singly-linked list. * struct ListNode { * int val; * struct ListNode *next; * }; */ struct ListNode* mergeTwoLists(struct ListNode* l1, struct ListNode* l2) { struct ListNode* head = malloc(sizeof(struct ListNode)); struct ListNode* p = head; while(l1&&l2){ if(l1->val < l2->val){ p->next = l1; l1 = l1->next; } else{ p->next = l2; l2 = l2->next; } p = p->next; } while(l1){ p->next = l1; l1 = l1->next; p = p->next; } while(l2){ p->next = l2; l2 = l2->next; p = p->next; } return head->next; }