从尾到头打印链表

Posted 2020-10-16 梵高先生

【题目】输入一个链表的头节点，从尾到头反过来打印每个节点的值。

 

1. 遍历的顺序是从头到尾，打印的顺序则是从尾到头，首先，想到栈，然后，递归的本质是一个栈结构，因此，想到用递归。

 1 import java.util.Stack;
 2 
 3 public class Main {
 4 
 5     Stack<Node> stack = new Stack<Node>();
 6 
 7     public static void main(String[] args) {
 8 
 9         Node node4 = new Node(4, null);
10         Node node3 = new Node(3, node4);
11         Node node2 = new Node(2, node3);
12         Node node1 = new Node(1, node2);
13         Node node0 = new Node(0, node1);
14 
15         Main main = new Main();
16 
17         main.process(node0);
18         main.process2(node0);
19 
20     }
21 
22     // 递归实现
23     public void process(Node head) {
24 
25         if (null != head) {
26 
27             if (null != head.next) {
28                 process(head.next);
29             }
30 
31             System.out.print(head.value + " ");
32         }
33     }
34 
35     // 栈实现
36     public void process2(Node head) {
37 
38         Node p = head;
39 
40         while (null != p) {
41             stack.add(p);
42             p = p.next;
43         }
44 
45         while (!stack.isEmpty()) {
46             System.out.print(stack.pop().value + " ");
47         }
48     }
49 }
50 
51 class Node {
52     int value;
53     Node next;
54 
55     public Node(int value, Node nextNode) {
56         this.value = value;
57         this.next = nextNode;
58     }
59 }