剑指Offer 第15题 链表中倒数第K个数

import java.util.Scanner;

public class Test{
//尾插法建立链表
public static ListNode createList(ListNode headNode) {
ListNode p=headNode;
if(p==null) {
return null;
}
Scanner sc=new Scanner(System.in);
System.out.println(“输入链表值，以0结尾”);
int input=sc.nextInt();
while(input!=0) {
ListNode q=new ListNode(input);
p.next=q;
p=q;
input=sc.nextInt();

	}
	
	return headNode;
}
//打印链表
public static void print(ListNode headNode) {
	if(headNode==null)return;
	while(headNode!=null) {
		System.out.println(headNode.data);
		headNode=headNode.next;
	}
}
//找到倒数第k个数
public static ListNode find(ListNode headNode,int k) {
	if(headNode==null||k<=0)return null;
	ListNode p1=headNode;
	ListNode p2=headNode;
	for(int i=0;i<k-1;i++) {
		if(p1.next!=null) {
			p1=p1.next;
		}else {
			return null;
		}
	}
	while(p1.next!=null) {
		p1=p1.next;
		p2=p2.next;
	}
	return p2;
}
public static void main(String[] args) {
	ListNode headNode = new ListNode(0);
	createList(headNode);
	print(headNode);
	System.out.println("请输入k值");
	Scanner sc = new Scanner(System.in);
	int k=sc.nextInt();
	System.out.println("倒数第"+k+"个数是"+find(headNode, k).data);
	
}

}
class ListNode{
int data;
ListNode next;
ListNode (int x){
data=x;
next=null;
}
}