LeetCode : Merge Two Sorted Lists [java]

最新推荐文章于 2025-11-15 17:45:46 发布

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#LeetCode #Merge Two Sorted Lis

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本文介绍了一种使用归并排序的思想来合并两个已排序的链表的方法，并提供了一个具体的Java实现示例。通过比较节点值，该算法可以高效地合并链表。

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.

思路：归并排序。

/**
 * 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) {
        if(l1 == null){
            return l2;
        }
        if(l2 == null){
            return l1;
        }
		ListNode head = null;
		ListNode p = null;
		if (l1.val < l2.val) {
			head = l1;
			p = head;
			l1 = l1.next;
		} else {
			head = l2;
			p = head;
			l2 = l2.next;
		}
		while (l1 != null && l2 != null) {
			if (l1.val < l2.val) {
				p.next = l1;
				p = p.next;
				l1 = l1.next;
			} else {
				p.next = l2;
				p = p.next;
				l2 = l2.next;
			}
		}
		while (l1 != null) {
			p.next = l1;
			p = p.next;
			l1 = l1.next;
		}
		while (l2 != null) {
			p.next = l2;
			p = p.next;
			l2 = l2.next;
		}
		return head;
    }
}