Merge Two Sorted Lists

最新推荐文章于 2022-05-22 13:07:29 发布

原创最新推荐文章于 2022-05-22 13:07:29 发布 · 303 阅读

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本文介绍了一种将两个已排序的链表合并为一个新排序链表的方法。使用哑节点简化了代码，并提供了完整的Java实现代码示例。

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Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

用了一个dumb head,。对于这种header不确定的list，可以用dumb header，代码会整洁不少。

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode dumHeader = new ListNode(0);
        ListNode current = dumHeader;
        while(l1 != null && l2 != null){
            ListNode nextNode = null;
            if(l1.val > l2.val){
                nextNode = l2;
                l2 = l2.next;
                current.next = nextNode;
                current = nextNode;
            }
            else if(l2.val >= l1.val){
                nextNode = l1;
                l1 = l1.next;
                current.next = nextNode;
                current = nextNode;
            }
        }
        
        if(l1 != null){
            current.next = l1;
        }
        else if (l2 != null){
            current.next = l2;
        }
        
        return dumHeader.next;
    }
}