LeetCode 21 -- Merge Two Sorted Lists

 1  public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
 2  
 3         ListNode p1 = l1;
 4         ListNode p2 = l2;
 5  
 6         ListNode fakeHead = new ListNode(0);
 7         ListNode p = fakeHead;
 8  
 9         while(p1 != null && p2 != null){
10           if(p1.val <= p2.val){
11               p.next = p1;
12               p1 = p1.next;
13           }else{
14               p.next = p2;
15               p2 = p2.next;
16           }
17  
18           p = p.next;
19         }
20  
21         if(p1 != null)
22             p.next = p1;
23         if(p2 != null)
24             p.next = p2;
25  
26         return fakeHead.next;
27     }