JZ16 合并两个排序的链表

https://www.nowcoder.com/practice/d8b6b4358f774294a89de2a6ac4d9337

/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode Merge(ListNode list1,ListNode list2) {
        ListNode result = new ListNode(0);
        ListNode temp = result;
        while(list1 != null || list2 != null) {
            // list1 == null 那 list2 肯定不为 null
            // 这两个判断主要是用于另一个 list 为空时的收尾工作
            if (list1 == null) {
                temp.next = list2;
                list2 = list2.next;
                temp = temp.next;
                continue;
            }
            
            if (list2 == null) {
                temp.next = list1;
                list1 = list1.next;
                temp = temp.next;
                continue;
            }
            
            if (list1.val > list2.val) {
                temp.next = list2;
                list2 = list2.next;
                temp = temp.next;
            } else {
                temp.next = list1;
                list1 = list1.next;
                temp = temp.next;
            }
            
        }
        
        return result.next;
    }
}