Leetcode - Merge Two Sorted Lists

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        if (l1 == null)
return l2;
else if (l2 == null)
return l1;
else if (l1 == null || l2 == null)
return null;


ListNode ln = new ListNode(0);
ListNode temp = ln;
while (l1 != null && l2 != null) {
if (l1.val < l2.val) {
temp.next = l1;
l1 = l1.next;
} else {
temp.next = l2;
l2 = l2.next;
}
temp = temp.next;
}
if (l2 != null)
temp.next = l2;
else if (l1 != null)
temp.next = l1;


return ln.next;
    }

}

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链表距离是3， 第一个新Node.NEXT ->LIST ; 第二 List 后移； 第三Node = node.next;

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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.