//在双链表删除倒数第k个节点
public class DoubleNode{
    public int value;
    public DoubleNode last;
    public DoubleNode next
    public DoubleNode(int data){
        this.data.data;
    }
}
public DoubleNode removeLastKthNode(DoubleNode head,int lastKth){
    if(head==null||lastKth<1){
        return head;
    }
    DoubleNode cur=head;
    while(cur!=null){
        lastKth--;
        cur=cur.next;
    }
    if(lastKth==0){
        head=head.next;
        head.last=null;
    }
    if(lastKth<0){
        cur=head;
        while(++lastKth!=0){
            cur=.cur.next;
        }
        DoubleNode newNext=cur.next.next;
        cur.next=newNext;
        if(newNext!=null){
            newNext.last=cur;
        }
    }
    return head;
}