Java实现单链表反转

本文主要介绍单链表反转的两种方法，记录如下：

1.

package com.leetcode;

public class ListReverse {

 public static void main(String[] args) {
  Node node1 = new Node(1);
  Node node2 = new Node(2);
  Node node3 = new Node(3);
  Node node4 = new Node(4);
  node1.next = node2;
  node2.next = node3;
  node3.next = node4;
  
  Node head = reverse(node1);
  while(head != null){
   System.out.println(head.val);
   head = head.next;
  }
  
 }
 
 public static Node reverse(Node head){
  Node cur = head, post = head.next;
  head.next = null;
  while(post != null){
   Node tmp = post;
   post = post.next;
   tmp.next = cur;
   cur = tmp;
  }
  return cur;
 }
 
 static class Node{
  int val;
  Node next;
  Node(int val){
   this.val = val;
   this.next = null;
  }
 }

}

运行结果为：

2.

package com.leetcode;

public class ListReverse {

 public static void main(String[] args) {
  Node node1 = new Node(1);
  Node node2 = new Node(2);
  Node node3 = new Node(3);
  Node node4 = new Node(4);
  node1.next = node2;
  node2.next = node3;
  node3.next = node4;
  
  Node head = reverse(node1);
  while(head != null){
   System.out.println(head.val);
   head = head.next;
  }
  
 }
 
 public static Node reverse(Node head){
  Node dummy = new Node(-1);
  dummy.next = head;
  Node pre = dummy, cur = head, post = head.next;
  while(post != null){
   cur.next = post.next;
   post.next = pre.next;
   pre.next = post;
   post = cur.next;
  }
  return dummy.next;
 }
 
 static class Node{
  int val;
  Node next;
  Node(int val){
   this.val = val;
   this.next = null;
  }
 }

}

运行结果为：