/** * struct ListNode { * int val; * struct ListNode *next; * }; */ class Solution { public: /** * * @param l1 ListNode类 * @param l2 ListNode类 * @return ListNode类 */ ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) { // write code here if (l1 == nullptr) { return l2; } else if (l2 == nullptr) { return l1; } ListNode* newHead = nullptr; if (l1->val < l2->val) { newHead = l1; newHead->next = mergeTwoLists(l1->next, l2); } else { newHead = l2; newHead->next = mergeTwoLists(l1, l2->next); } return newHead; } };