【链表】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.

/** * 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;        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 if(l2 == null) p.next = l1;        head = head.next;        return head;    }}