查找双向链表大小的程序

给定一个双向链表，任务是找到该双向链表的大小。例如，下面链表的大小是 4。

双向链表是一种链接数据结构，由一组称为节点的顺序链接记录组成。每个节点包含两个字段，称为链接，它们是对节点序列中前一个节点和下一个节点的引用。
双向链表的遍历可以是任一方向。事实上，如果需要，遍历的方向可以改变很多次。

例如，对于上述双向链表，该函数应返回 3。

算法 ：

1) 将大小初始化为 0。
2）初始化一个节点指针，temp=head。
3) 在 temp 不为 NULL 时执行以下操作
……a) 温度 = 温度 -> 下一个
……b) 尺寸++；
4) 返回大小。

C++

// A complete working C++ program to
// find size of doubly linked list.
#include 
using namespace std;
 
// A linked list node
struct Node
{
    int data;
    struct Node *next;
    struct Node *prev;
};
 
/* Function to add a node to front of doubly
   linked list */
void push(struct Node** head_ref, int new_data)
{
    struct Node* new_node = new Node;
    new_node->data  = new_data;
    new_node->next = (*head_ref);
    new_node->prev = NULL;
    if ((*head_ref) !=  NULL)
      (*head_ref)->prev = new_node ;
    (*head_ref)    = new_node;
}
 
// This function returns size of linked list
int findSize(struct Node *node)
{
   int res = 0;
   while (node != NULL)
   {
       res++;
       node = node->next;
   }
   return res;
}
 
/* Driver program to test above functions*/
int main()
{
    struct Node* head = NULL;
    push(&head, 4);
    push(&head, 3);
    push(&head, 2);
    push(&head, 1);
    cout << findSize(head);
    return 0;
}

Java

// A complete working Java program to
// find size of doubly linked list.
import java.io.*;
import java.util.*;
 
// Represents a doubly linked list node
class Node
{
    int data;
    Node next, prev;
    Node(int val)
    {
        data = val;
        next = null;
        prev = null;
    }
}
 
class GFG
{
 
    /* Function to add a node to front of doubly
    linked list */
    static Node push(Node head, int data)
    {
        Node new_node = new Node(data);
        new_node.next = head;
        new_node.prev = null;
        if (head != null)
            head.prev = new_node;
        head = new_node;
             
        return head;
    }
 
    // This function returns size of doubly linked list
    static int findSize(Node node)
    {
        int res = 0;
        while (node != null)
        {
                res++;
                node = node.next;
        }
 
        return res;
    }
 
    // Driver Code
    public static void main(String args[])
    {
        Node head = null;
        head = push(head, 4);
        head = push(head, 3);
        head = push(head, 2);
        head = push(head, 1);
        System.out.println(findSize(head));
    }
}
 
// This code is contributed by rachana soma

Python3

# A complete working Python3 program to
# find size of doubly linked list.
 
# A linked list node
class Node:
    def __init__(self):
        self.data = None
        self.next = None
        self.prev = None
 
# Function to add a node to front of doubly
# linked list
def push( head_ref, new_data):
 
    new_node = Node()
    new_node.data = new_data
    new_node.next = (head_ref)
    new_node.prev = None
    if ((head_ref) != None):
        (head_ref).prev = new_node
    (head_ref) = new_node
    return head_ref
 
# This function returns size of linked list
def findSize(node):
 
    res = 0
    while (node != None):
        res = res + 1
        node = node.next
     
    return res
 
# Driver code
head = None
head = push(head, 4)
head = push(head, 3)
head = push(head, 2)
head = push(head, 1)
print(findSize(head))
 
# This code is contributed by Arnab Kundu

C#

// A complete working C# program to
// find size of doubly linked list.
 using System;
 
// Represents a doubly linked list node
public class Node
{
    public int data;
    public Node next, prev;
    public Node(int val)
    {
        data = val;
        next = null;
        prev = null;
    }
}
 
class GFG
{
 
    /* Function to add a node to front of doubly
    linked list */
    static Node push(Node head, int data)
    {
        Node new_node = new Node(data);
        new_node.next = head;
        new_node.prev = null;
        if (head != null)
            head.prev = new_node;
        head = new_node;
             
        return head;
    }
 
    // This function returns size of doubly linked list
    static int findSize(Node node)
    {
        int res = 0;
        while (node != null)
        {
                res++;
                node = node.next;
        }
 
        return res;
    }
 
    // Driver Code
    public static void Main(String []args)
    {
        Node head = null;
        head = push(head, 4);
        head = push(head, 3);
        head = push(head, 2);
        head = push(head, 1);
        Console.WriteLine(findSize(head));
    }
}
 
// This code is contributed by Arnab Kundu

Javascript

// A complete working javascript program to
// find size of doubly linked list.
// Represents a doubly linked list node
 class Node {
        constructor(val) {
            this.data = val;
            this.prev = null;
            this.next = null;
        }
    }
    /*
     * Function to add a node to front of doubly linked list
     */
    function push(head , data) {
var new_node = new Node(data);
        new_node.next = head;
        new_node.prev = null;
        if (head != null)
            head.prev = new_node;
        head = new_node;
 
        return head;
    }
 
    // This function returns size of doubly linked list
    function findSize(node) {
        var res = 0;
        while (node != null) {
            res++;
            node = node.next;
        }
 
        return res;
    }
 
    // Driver Code
     
var head = null;
        head = push(head, 4);
        head = push(head, 3);
        head = push(head, 2);
        head = push(head, 1);
        document.write(findSize(head));
 
// This code contributed by aashish1995

输出：

4

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