给定链表的头结点head，整数a、b，实现删除链表的中间节点的函数，并实现删除位于a/b处节点的函数。

public class RemoveNode {
    public class Node{
        public int value;
        public Node next;
        public Node(int data){
            value=data;
        }
    }
public Node removeMidNode(Node head){
    if(head==null||head.next==null){
        return head;
    }
    if(head.next.next==null){
        return head.next;
    }
    Node pre=head;
    Node cur=head.next.next;
    while(cur.next!=null&&cur.next.next!=null){
        pre=pre.next;
        cur=cur.next.next;
    }
    pre.next=pre.next.next;
    return head;
}
public Node removeByRatio(Node head,int a,int b){
    if(a<1||a>b){
        return head;
    }
    int n=0;
    Node cur=head;
    while(cur!=null){
        n++;
        cur=cur.next;
    }
    n=(int)Math.ceil(((double)(a*n))/(double)b);
    if(n>1){
        cur=head;
        while(--n!=1){
            cur=cur.next;
        }
        cur.next=cur.next.next;
    }
    return head;
}
}