与倒数第N个节点相关的题目

基础链表构造：

public class ListNode {public int val;public ListNode next;public ListNode(int val, ListNode next) {super();this.val = val;this.next = next;}public ListNode(int val) {super();this.val = val;}public static ListNode arrayToList(int[] arr) {ListNode head = new ListNode(0);ListNode p = head;for(int value : arr){p.next = new ListNode(value);p = p.next;}return head.next;}public static void printList(ListNode head){ListNode p = head;while(p != null){System.out.print(p.val + " ");p = p.next;}System.out.println();}}

相关面试题：

public class 倒数第N个节点 {public static void main(String[] args){int[] array = {1,2,3,4,5,5,5,6,7,8};ListNode head = ListNode.arrayToList(array);ListNode.printList(head);int n = lengthOfList(head);System.out.println(n);int x = 3;System.out.println(getLastNth(head,x).val);//查询倒数第N个节点int d = 3;deleteLastNth(head,d);//删除倒数第N个节点ListNode.printList(head);removeElements(head,5);ListNode.printList(head);//查询节点并删除}/** * 删除掉指定的某个元素 * @param head * @param i */private static void removeElements(ListNode head, int i) {ListNode pre = head;   //定义双指针，目的是找到将要删除节点的前一个节点，以便执行删除操作ListNode p = head;while(p != null){if(p.val == i){pre.next = p.next;p = p.next;}else{pre = p;p = p.next;}}}/** * 删除倒数第N个节点 * @param head * @param d */private static void deleteLastNth(ListNode head, int d) {ListNode p = head;ListNode pre = head;for(int i = 0; i < d+1; i++){//多加1，就是返回要删除节点的前一个节点的位置p = p.next;}while(p != null){//多加1，就是返回要删除节点的前一个节点的位置p = p.next;pre = pre.next;}pre.next = pre.next.next;}/** * 查找倒数第N个节点 * @param head * @param x * @return */private static ListNode getLastNth(ListNode head,int x) {ListNode p = head;ListNode pre = head;for(int i = 0; i < x; i++){p = p.next;}while(p != null){p = p.next;pre = pre.next;}return pre;}/** * 链表长度 * @param head * @return */private static int lengthOfList(ListNode head) {int count = 0;ListNode p = head;while(p != null){count++;p = p.next;}return count;}}