LeetCode 21. Merge Two Sorted Lists

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.

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连接两个有序链表 基础题 不多说
/**
* 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 = new ListNode(0);
ListNode p = head;
while(l1!=null&&l2!=null){
if(l1.val<l2.val){
p.next = l1;
l1 = l1.next;
}
else{
p.next = l2;
l2 = l2.next;
}
p = p.next;
}
if(l1==null){
p.next = l2;
}
else p.next = l1;
return head.next;
}
}