反转单链表

package com.harrison.class02;
import java.util.ArrayList;
import java.util.List;
public class Code01_ReverseLinkedList {
  public static class Node {
    public int value;
    public Node next;
    public Node(int v) {
      this.value = v;
    }
  }
  public static Node reverseLinkedList(Node head) {
    Node pre = null;
    Node next = null;
    while (head != null) {
      next = head.next;
      head.next = pre;
      pre = head;
      head = next;
    }
    return pre;
  }
  public static Node generateRandomLinkedList(int len, int value) {
    int size = (int) (Math.random() * (len + 1));
    if (size == 0) {
      return null;
    }
    size--;
    Node head = new Node((int) (Math.random() * (value + 1)));
    Node pre = head;
    while (size != 0) {
      Node cur = new Node((int) (Math.random() * (value + 1)));
      pre.next = cur;
      pre = cur;
      size--;
    }
    return head;
  }
  public static List<Integer> getLinkedListOriginalOrder(Node head){
    List<Integer> ans=new ArrayList<>();
    while(head!=null) {
      ans.add(head.value);
      head=head.next;
    }
    return ans;
  }
  public static boolean checkedLinkedListReverse(List<Integer> origin,Node head) {
    for(int i=origin.size()-1; i>=0; i--) {
      if(!origin.get(i).equals(head.value)) {
        return false;
      }
      head=head.next;
    }
    return true;
  }
  public static Node testReverseLinkedList(Node head) {
    if(head==null) {
      return null;
    }
    ArrayList<Node> list=new ArrayList<>();
    while(head!=null) {
      list.add(head);
      head=head.next;
    }
    list.get(0).next=null;
    int N=list.size();
    for(int i=1; i<N; i++) {
      list.get(i).next=list.get(i-1);
    }
    return list.get(N-1);
  }
  public static void main(String[] args) {
    int len = 100;
    int value = 100;
    int testTimes = 1000000;
    System.out.println("test begin");
    for (int i = 0; i < testTimes; i++) {
      Node node1=generateRandomLinkedList(len, value);
      List<Integer> list1=getLinkedListOriginalOrder(node1);
      node1=reverseLinkedList(node1);
      if(!checkedLinkedListReverse(list1, node1)) {
        System.out.println("Oops1!");
      }
      Node node2=generateRandomLinkedList(len, value);
      List<Integer> list2=getLinkedListOriginalOrder(node2);
      node2=testReverseLinkedList(node2);
      if(!checkedLinkedListReverse(list2, node2)) {
        System.out.println("Oops2!");
      }
    }
    System.out.println("finish");
  }
}