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单链表表面试题：
1、题目：
? ? ? ? 1）求单链表中有效节点个数
????????2）查找单链表中倒数第K个节点
????????3）单链表的反转
? ? ? ? 4）逆序打印单链表
????????5）打卡第三天与第六天总代码
2、代码实现：
????????1）求单链表中有效节点个数
public static int getLength(HeroNode head){
if(head.next == null){
return 0;
}
int length = 0;
HeroNode temp = head.next;
while(temp != null){
length++;
temp = temp.next;
}
return length;
}
? ? ? ? 2）查找单链表中倒数第K个节点
public static HeroNode findLastIndexNode(HeroNode head, int index){
if(head.next == null){
return null;
}
int size = getLength(head);
if(index <=0 || index > size){
return null;
}
HeroNode temp = head.next;
for(int i = 0; i < size - index; i++){
temp = temp.next;
}
return temp;
}
? ? ? ? 3）单链表的反转
public void reversetList(HeroNode head){
if(head.next == null || head.next.next == null){
return;
}
HeroNode temp = head.next;
HeroNode next = null;
HeroNode reverseHead = new HeroNode(0, "", "");
while(temp != null){
next = temp.next;
temp.next = reverseHead.next;
reverseHead.next = temp;
temp = next;
}
head.next = reverseHead.next;
}
????????4）逆序打印单链表
public static void reversePrint(HeroNode head){
if(head.next == null){
return;
}
Stack<HeroNode> stack = new Stack<HeroNode>();
HeroNode temp = head.next;
while(temp != null){
stack.push(temp);
temp = temp.next;
}
while(stack.size() > 0){
System.out.println(stack.pop());
}
}
? ? ? ? 5）打卡第三天与第六天总代码
package linkedList;
import java.util.Stack;
public class SingleLinkedListDemo {
public static void main(String[] args) {
// TODO Auto-generated method stub
HeroNode hero1 = new HeroNode(1, "宋江" , "及时雨");
HeroNode hero2 = new HeroNode(2, "卢俊义" , "玉麒麟");
HeroNode hero3 = new HeroNode(3, "吴用" , "智多星");
HeroNode hero4 = new HeroNode(4, "林冲" , "豹子头");
SingleLinkedList singleLinkedList = new SingleLinkedList();
// singleLinkedList.addList(hero1);
// singleLinkedList.addList(hero3);
// singleLinkedList.addList(hero4);
// singleLinkedList.addList(hero2);
// singleLinkedList.showList();
singleLinkedList.addByOrder(hero1);
singleLinkedList.addByOrder(hero3);
singleLinkedList.addByOrder(hero4);
singleLinkedList.addByOrder(hero2);
singleLinkedList.showList();
HeroNode newHeroNode = new HeroNode(2, "小卢" , "玉麒麟~");
singleLinkedList.update(newHeroNode);
System.out.println("修改后：");
singleLinkedList.showList();
singleLinkedList.delList(4);
System.out.println("删除后：");
singleLinkedList.showList();
System.out.println("有效节点个数为：" + getLength(singleLinkedList.getHead()));
System.out.println("倒数第"+"index"+"d个节点是：" + findLastIndexNode(singleLinkedList.getHead(), 1));
System.out.println("反转单链表：");
singleLinkedList.reversetList(singleLinkedList.getHead());
singleLinkedList.showList();
System.out.println("逆序打印（没有改变链表结构）：");
reversePrint(singleLinkedList.getHead());
}
public static void reversePrint(HeroNode head){
if(head.next == null){
return;
}
Stack<HeroNode> stack = new Stack<HeroNode>();
HeroNode temp = head.next;
while(temp != null){
stack.push(temp);
temp = temp.next;
}
while(stack.size() > 0){
System.out.println(stack.pop());
}
}
public static HeroNode findLastIndexNode(HeroNode head, int index){
if(head.next == null){
return null;
}
int size = getLength(head);
if(index <=0 || index > size){
return null;
}
HeroNode temp = head.next;
for(int i = 0; i < size - index; i++){
temp = temp.next;
}
return temp;
}
public static int getLength(HeroNode head){
if(head.next == null){
return 0;
}
int length = 0;
HeroNode temp = head.next;
while(temp != null){
length++;
temp = temp.next;
}
return length;
}
}
class SingleLinkedList {
HeroNode head = new HeroNode(0, "", "");
public HeroNode getHead(){
return head;
}
public void addList(HeroNode heroNode){
HeroNode temp = head;
while(true){
if(temp.next == null){
break;
}
temp = temp.next;
}
temp.next = heroNode;
}
//不考虑编号顺序
public void showList(){
if(head.next == null){
System.out.println("链表为空");
return;
}
HeroNode temp = head.next;
while(true){
if(temp == null){
break;
}
System.out.println(temp);
temp = temp.next;
}
}
//考虑标号顺序
public void addByOrder(HeroNode heroNode){
HeroNode temp = head;
boolean flag = false;
while(true){
if(temp.next == null){
break;
}
if(temp.next.no > heroNode.no){
break;
}else if(temp.next.no == heroNode.no){
flag = true;
break;
}
temp = temp.next;
}
if(flag){
System.out.printf("准备插入的英雄编号%d已经存在了，不能加入了。\n", heroNode.no);
}else{
heroNode.next = temp.next;
temp.next = heroNode;
}
}
public void update(HeroNode newHeroNode){
if(head.next == null){
System.out.println("链表为空");
return;
}
HeroNode temp = head.next;
boolean flag = false;
while(true){
if(temp == null){
break;
}
if(temp.no == newHeroNode.no){
flag = true;
break;
}
temp = temp.next;
}
if(flag){
temp.name = newHeroNode.name;
temp.nickName = newHeroNode.nickName;
}else{
System.out.printf("没有找到编号%d的节点，不能修改。\n", newHeroNode.no);
}
}
public void delList(int no){
HeroNode temp = head;
boolean flag = false;
while(true){
if(temp.next == null){
break;
}
if(temp.next.no == no){
flag = true;
break;
}
temp = temp.next;
}
if(flag){
temp.next = temp.next.next;
}else{
System.out.printf("要删除的%d节点不存在\n", no);
}
}
public void reversetList(HeroNode head){
if(head.next == null || head.next.next == null){
return;
}
HeroNode temp = head.next;
HeroNode next = null;
HeroNode reverseHead = new HeroNode(0, "", "");
while(temp != null){
next = temp.next;
temp.next = reverseHead.next;
reverseHead.next = temp;
temp = next;
}
head.next = reverseHead.next;
}
}
class HeroNode {
public int no;
public String name;
public String nickName;
public HeroNode next;
public HeroNode(int no, String name, String nickName){
this.no = no;
this.name = name;
this.nickName = nickName;
}
public String toString(){
return "HeroNode=["+"no = " + no + "，name = " + name + "，nickName = " + nickName + "]";
}
}
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