10.02日练

单链表中的节点应该具有两个属性:val 和 next。val 是当前节点的值,next 是指向下一个节点的指针/引用。https://blog.csdn.net/qq_37264323/article/details/114366943

递归

https://leetcode.cn/problems/merge-two-sorted-lists/

class Solution {
public:
    ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
        if (l1 == nullptr) {
            return l2;
        }
        else if (l2 == nullptr) {
            return l1;
        } 
        else if (l1->val < l2->val) {
            l1->next = mergeTwoLists(l1->next, l2);
            return l1;
        }
        else {
            l2->next = mergeTwoLists(l1, l2->next);
            return l2;
        }
    }
}