剑指offer——合并两个有序的链表

/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode Merge(ListNode l1,ListNode l2) {
        if(l1==null)
            return l2;
        if(l2==null)
            return l1;
        
        ListNode head = new ListNode(-1);
        ListNode merge = head;
        
        while(l1!=null&&l2!=null)
        {
            if(l1.val<l2.val)
            {
                merge.next =l1;
                merge = merge.next;
                l1 = l1.next;
            }
            else
            {
                merge.next = l2;
                merge = merge.next;
                l2 = l2.next;
            }
        }
        if(l1!=null)
        {
            merge.next = l1;
        }
        if(l2!=null)
        {
            merge.next = l2;
        }
        return head.next;
        
    }
}