LeetCode 21 合并两个有序链表

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* mergeTwoLists(ListNode* list1, ListNode* list2) {
        ListNode* cur1 = list1;
        ListNode* cur2 = list2;
        ListNode* temp = new ListNode(0);
        ListNode* res = temp;

        while (cur1 && cur2) {
            if (cur1 ->val <= cur2 ->val) {
                temp ->next = cur1;
                cur1 = cur1 ->next;
                
            }
            else {
                temp ->next = cur2;
                cur2 = cur2 ->next;
            }
            temp = temp ->next;
        }
        //扫尾
        while (cur1) temp ->next = cur1, temp = temp ->next, cur1 = cur1 ->next;
        while (cur2) temp ->next = cur2, temp= temp ->next, cur2 = cur2 ->next;

        return res ->next;
    }
};