package com.imood.msjava;

/**

* @description:

* @author: msJava

* @createDate: 2020/07/02

* @version: 1.0

*/

public class Test {

/**

* 输入单链表的倒数第N个元素

*

* @param head

* @param N

* @return

*/

public int kthToLast(ListNode head, int N) {

//双指针法

int a;

ListNode pre = head;

ListNode low = head;

if (head.next == null) {

return head.val;

}

//先让pre在单链表上走N步，然后两个一起走，

// pre到链表尾部时，low刚好位于链表倒数第N个节点上，直接返回该节点即可

for (int i = 0; i < N; i++) {

pre = pre.next;

}

while (pre != null) {

pre = pre.next;

low = low.next;

}

return low.val;

}

/**

* 单链表实体

*/

class ListNode {

int val;

ListNode next;

ListNode(int x) {

val = x;

}

}

}