Leetcode-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.

AC代碼：

public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        if( l1 == null && l2 == null ) return null;
		if( l1 == null ) return l2;
		if( l2 == null ) return l1;
		ListNode p = l1;
		ListNode q = l2;
		ListNode dummyHead = new ListNode(-1);
		ListNode dummyCurr = dummyHead;
		while( p != null && q != null ){
			if( p.val <= q.val){
				dummyCurr.next = p;
				p = p.next;
				dummyCurr = dummyCurr.next;
			}else{
				dummyCurr.next = q;
				q = q.next;
				dummyCurr = dummyCurr.next;
			}
		}
		if( p == null ) dummyCurr.next = q;
		if( q == null ) dummyCurr.next = p;
		return dummyHead.next;
    }
}