Java單鏈表的三個面試題：

1、將單鏈表反轉

2、從尾到頭輸出單鏈表

3、輸出單鏈表的倒數第k個節點

 1 import java.util.Stack;
 2 
 3 /**
 4  * @author ZhiYi Li
 5  * @create 2020/8/25 20:45
 6  */
 7 public class SingleLinkedTest {
 8     //問題1：查詢單鏈表中倒數第k個節點
 9     //普通思路，先計算連結串列長度，然後用長度減去k得到順序數的位置
10     //更裝逼的思路，快慢指標思路，定義一個rear=1，定義一個front為k
11     //，先讓front先走k個單位，之後front和rear同步增加，當front走到尾部時，rear就是在倒數k個的位置上
 

12     public static HeroNode getReciprocalK(HeroNode head,int k){
13         if(head.next == null){
14             return null;
15         }
16         HeroNode front = head;
17         HeroNode rear = head;
18         int i;
19         for (i = 0; i < k&&front!=null; i++) {
20             front = front.next;
 
21         }
22         if(i<k){
23             return null;
24         }
25         while (front!=null){
26             front = front.next;
27             rear = rear.next;
28         }
29         return rear;
30     }
31     //問題二：反轉單鏈表（頭插法）
32     public static void reverseNode(HeroNode head){
33
 
         if(head.next == null||head.next.next==null){
34             return;
35         }
36         HeroNode temp = new HeroNode(0,"");//新頭節點
37         HeroNode temp2 = head.next;
38         HeroNode temp3;
39         while (temp2!=null){
40             temp3 = temp2.next;
41             temp2.next = temp.next;
42             temp.next = temp2;
43             temp2 = temp3;
44         }
45         head.next = temp.next;
46     }
47     //問題三：從尾到頭列印單鏈表
48     public static void printRearToFront(HeroNode head){
49         //方式一：遞迴輸出,無法不讓頭節點輸出，遞迴效能差，不建議使用
50         //其實也能讓頭節點不輸出，將以下程式碼重寫一個方法，將head.next傳入
51 //        HeroNode temp = head;
52 //        if(temp!=null){
53 //            printRearToFront(temp.next);
54 //            System.out.println(temp);
55 //        }
56         //方式二：使用棧Stack,利用棧的特性來寫
57         if(head.next == null){
58             return;
59         }
60         Stack<HeroNode> stack = new Stack<>();
61         HeroNode temp = head.next;
62         while (temp!=null){
63             stack.add(temp);
64             temp=temp.next;
65         }
66         while (stack.size()>0){
67             System.out.println(stack.pop());
68         }
69     }
70     public static void main(String[] args) {
71         SingleLinkedList linkedList = new SingleLinkedList();
72         linkedList.addNodeByNo2(new HeroNode(0,"張三"));
73         linkedList.addNodeByNo2(new HeroNode(1,"李四"));
74         linkedList.addNodeByNo2(new HeroNode(4,"王五"));
75         linkedList.addNodeByNo2(new HeroNode(2,"趙六"));
76         linkedList.addNodeByNo2(new HeroNode(3,"吳七"));
77         linkedList.show();
78         System.out.println("倒數第k個節點：");
79         System.out.println(getReciprocalK(linkedList.getHead(),5));
80         linkedList.show();
81         System.out.println("反轉單鏈表：");
82         reverseNode(linkedList.getHead());
83         linkedList.show();
84         System.out.println("從後往前列印單鏈表");
85         printRearToFront(linkedList.getHead());
86     }
87 
88 }