使用java编写两个方法min和max来查找链表中的最大值和最小值，但输入列表是整数数组

Question

• 我想写两个方法min和max来查找链表中节点的最大值和最小值
• 例如，如果一个名为abc的变量存储｛1，78，-9，42，0，14｝，则abc.min((应返回-9，abc.max((则应返回78

• 如果列表为空，则应返回-1。打印返回的值

  请帮助我如何通过输入整数数组来计算链表中的最大值和最小值

  ```package demo;
  public class MaximumMinimum {
  class Node{  
  int data;  
  Node next;  
  public Node(int data) {  
  this.data = data;  
  this.next = null;  
  }  
  }  
  //Represent the head and tail of the singly linked list 
  public Node head = null;  
  public Node tail = null;  
  //addNode() will add a new node to the list  
  public void addNode(int data) {  
  //Create a new node  
  Node newNode = new Node(data);  
  //Checks if the list is empty  
  if(head == null) {  
  //If list is empty, both head and tail will point to new node  
  head = newNode;  
  tail = newNode;  
  }  
  else {  
  //newNode will be added after tail such that tail's next will point to newNode  
  tail.next = newNode;  
  //newNode will become new tail of the list  
  tail = newNode;  
  }  
  }  
  //minNode() will find out the minimum value node in the list  
  public void minNode() {  
  Node current = head;  
  int min;  
  if(head == null) {  
  System.out.println("List is empty");  
  }  
  else {  
  //Initializing min with head node data  
  min = head.data;  
  while(current != null){  
  //If current node's data is smaller than min  
  //Then, replace value of min with current node's data  
  if(min > current.data) {  
  min = current.data;  
  }  
  current= current.next;  
  }  
  System.out.println("Minimum value node in the list: "+ min);  
  }  
  }  
  //maxNode() will find out the maximum value node in the list  
  public void maxNode() {  
  Node current = head;  
  int max;  
  if(head == null) {  
  System.out.println("List is empty");  
  }  
  else {  
  //Initializing max with head node data  
  max = head.data;  
  while(current != null){  
  //If current node's data is greater than max  
  //Then, replace value of max with current node's data  
  if(max < current.data) {  
  max = current.data;  
  }  
  current = current.next;  
  }  
  System.out.println("Maximum value node in the list: "+ max);  
  }  
  }  
  public static void main(String[] args) {
  MaximumMinimum sList = new MaximumMinimum(); 
  //Adds data to the list  
  sList.addNode(5);  
  sList.addNode(8);  
  sList.addNode(1);  
  sList.addNode(6);  
  //Display the minimum value node in the list  
  sList.minNode();  
  *//Display the maximum value node in the list *
  sList.maxNode();  
  }  
  }  ```
  

Answer 1

您给出的代码正在以正确的方式执行。

您也可以使用

MaximumMinimum sList = new MaximumMinimum(); 
List<Integer> list = new ArrayList<>();
Node head = sList.head;
while(head != null){
list.add(head.data);
head= head.next;
}
//no recommended if you want to design your own method    
System.out.println(list);
System.out.println(Collections.max(list));
System.out.println(Collections.min(list));

用于将整数数组输入到

public void stores(int[] array)
{
for(int element:array)
{
this.addNode(element);
}
}

然后如果你在主中运行

int[] elements = {1, 78, -9, 42 , 0, 14};
sList.stores(elements);
sList.maxNode(); //78
sList.minNode();//-9

如果你想用java8的方式来做，你也可以使用Arrays.stream(array_name).forEach(e->sList.add(e))。

Answer 2

您为minNode()函数设置了一个大于号，为maxNode()设置了小于号

public void minNode() {  
Node current = head;  
int min;  
if(head == null) {  
System.out.println("List is empty");  
}  
else {  
//Initializing min with head node data  
min = head.data;  
while(current != null){  
//If current node's data is smaller than min  
//Then, replace value of min with current node's data  

// Your error was here:
min = Math.min(min, current.data); // You can simplify updating min to this.


current= current.next;  
}  
System.out.println("Minimum value node in the list: "+ min);  
}  
}  

maxNode()变为：

public void maxNode() {  
Node current = head;  
int max;  
if(head == null) {  
System.out.println("List is empty");  
}  
else {  
//Initializing max with head node data  
max = head.data;  
while(current != null){  
//If current node's data is greater than max  
//Then, replace value of max with current node's data  

// Your error was here:
max = Math.max(max, current.data); // And updating max becomes this.


current = current.next;  
}  
System.out.println("Maximum value node in the list: "+ max);  
}  
}