创建指针&&遍历指针&&查找倒数第N个指针

package 找出倒数第N个结点;

public class Test {
    int size = 0;//大小
    static Node headNode;

    int i = 0;

    class Node {
        private Node next;//指针

        private int data;//数据域

    }

    //尾插法创建单链表  队列形式先进先出
    public void fun(Node node, int data) {
        if (i <= 10) {
            Node newNode = new Node();//创建新的结点
            newNode.data = i;//设置数据域
            newNode.next = null;
            node.next = newNode;
            fun(newNode, ++i);
        }
    }

    //头插法创建单链表  栈形式先进后出
    public void afterInsert(Node node, int data) {

        if (i <= 10) {
            Node newNode = new Node();//创建新的结点
            newNode.data = i;//设置数据域
            newNode.next = node.next;
            node.next = newNode;
            afterInsert(node, ++i);
        }

    }


    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Test test = new Test();
        headNode = test.new Node();//头指针
        new Test().fun(headNode, 0);//前插法
//            new Test().afterInsert(headNode,0);//后插法


        Node node=FindNthToTail(headNode,3);
        System.out.println("FindNthToTail===="+node.data + " ");


        System.out.println("创建后的链表是：");//0 1 2 3 4 5 6 7 8 9 10
        while (headNode.next != null) {
            headNode = headNode.next;
            System.out.print(headNode.data + " ");
        }

    }
    //查找倒数第N指针
    public static Node FindNthToTail(Node head, int N) {
        Node pre = head, p = head;
        int a=N;
        int count =0;
        while(p!=null){
            p=p.next;
            count++;
            if(N<1){
                pre=pre.next;
            }
            N--;
        }
        if(count<a) return null;
        return pre;

    }
}