30 Day Challenge Day 18 | Leetcode 701. Insert into a Binary Search Tree

题解

Easy

class Solution {
public:
    ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
        ListNode* prehead = new ListNode(0);
        ListNode* p = prehead;
        
        while(l1 || l2) {
            if(l1 && l2) {
                if(l1->val < l2->val) {
                    p->next = l1;
                    l1 = l1->next;
                } else {
                    p->next = l2;
                    l2 = l2->next;
                }
            } else if(l1) {
                p->next = l1;
                l1 = l1->next;
            } else {
                p->next = l2;
                l2 = l2->next;
            }
            p = p->next;
        }
        
        return prehead->next;
    }
};