循环链表中的节点计数
原文：https://www.geeksforgeeks.org/count-nodes-circular-linked-list/
给定一个循环链表，计算其中的节点数。 例如，以下列表的输出为 5。
我们使用循环链表 | 系列 2（遍历）中的概念。 在遍历时，我们会跟踪节点数。
C/C++
// C program to count number of nodes in
// a circular linked list.
#include <stdio.h>
#include <stdlib.h>
/* structure for a node */
struct Node {
int data;
struct Node* next;
};
/* Function to insert a node at the beginning
of a Circular linked list */
void push(struct Node** head_ref, int data)
{
struct Node* ptr1 = (struct Node*)malloc(sizeof(struct Node));
struct Node* temp = *head_ref;
ptr1->data = data;
ptr1->next = *head_ref;
/* If the linked list is not NULL then set
the next of last node */
if (*head_ref != NULL) {
while (temp->next != *head_ref)
temp = temp->next;
temp->next = ptr1;
} else
ptr1->next = ptr1; /*For the first node */
*head_ref = ptr1;
}
/* Function to print nodes in a given Circular
linked list */
int countNodes(struct Node* head)
{
struct Node* temp = head;
int result = 0;
if (head != NULL) {
do {
temp = temp->next;
result++;
} while (temp != head);
}
return result;
}
/* Driver program to test above functions */
int main()
{
/* Initialize lists as empty */
struct Node* head = NULL;
push(&head, 12);
push(&head, 56);
push(&head, 2);
push(&head, 11);
printf("%d", countNodes(head));
return 0;
}
Java
// Java program to count number of nodes in
// a circular linked list.
class GFG
{
/* ure for a node */
static class Node
{
int data;
Node next;
};
/* Function to insert a node at the beginning
of a Circular linked list */
static Node push( Node head_ref, int data)
{
Node ptr1 = new Node();
Node temp = head_ref;
ptr1.data = data;
ptr1.next = head_ref;
/* If linked list is not null then set
the next of last node */
if (head_ref != null)
{
while (temp.next != head_ref)
temp = temp.next;
temp.next = ptr1;
} else
ptr1.next = ptr1; /*For the first node */
head_ref = ptr1;
return head_ref;
}
/* Function to print nodes in a given Circular
linked list */
static int countNodes( Node head)
{
Node temp = head;
int result = 0;
if (head != null)
{
do
{
temp = temp.next;
result++;
} while (temp != head);
}
return result;
}
/* Driver program to test above functions */
public static void main(String args[])
{
/* Initialize lists as empty */
Node head = null;
head = push(head, 12);
head = push(head, 56);
head = push(head, 2);
head = push(head, 11);
System.out.printf("%d", countNodes(head));
}
}
// This code is contributed by Arnab Kundu
Python3
# Python3 program to count number of nodes in
# a circular linked list.
# structure for a node
class Node:
def __init__(self, data):
self.data = data
self.next = None
# Function to insert a node at the beginning
# of a Circular linked list */
def push(head_ref,data):
ptr1 = Node(0)
temp = head_ref
ptr1.data = data
ptr1.next = head_ref
# If the linked list is not None then set
# the next of last node
if (head_ref != None) :
while (temp.next != head_ref):
temp = temp.next
temp.next = ptr1
else:
ptr1.next = ptr1 #For the first node */
head_ref = ptr1
return head_ref
# Function to print nodes
# in a given Circular linked list
def countNodes(head):
temp = head
result = 0
if (head != None) :
while True :
temp = temp.next
result = result + 1
if (temp == head):
break
return result
# Driver Code
if __name__=='__main__':
# Initialize lists as empty */
head = None
head = push(head, 12)
head = push(head, 56)
head = push(head, 2)
head = push(head, 11)
print( countNodes(head))
# This code is contributed by Arnab Kundu
C
// C# program to count number of nodes in
// a circular linked list.
using System;
class GFG
{
/* structure for a node */
public class Node
{
public int data;
public Node next;
};
/* Function to insert a node at the beginning
of a Circular linked list */
static Node push( Node head_ref, int data)
{
Node ptr1 = new Node();
Node temp = head_ref;
ptr1.data = data;
ptr1.next = head_ref;
/* If linked list is not null then set
the next of last node */
if (head_ref != null)
{
while (temp.next != head_ref)
temp = temp.next;
temp.next = ptr1;
} else
ptr1.next = ptr1; /*For the first node */
head_ref = ptr1;
return head_ref;
}
/* Function to print nodes in a given Circular
linked list */
static int countNodes( Node head)
{
Node temp = head;
int result = 0;
if (head != null)
{
do
{
temp = temp.next;
result++;
} while (temp != head);
}
return result;
}
/* Driver code */
public static void Main(String []args)
{
/* Initialize lists as empty */
Node head = null;
head = push(head, 12);
head = push(head, 56);
head = push(head, 2);
head = push(head, 11);
Console.Write( countNodes(head));
}
}
// This code is contributed by Arnab Kundu
4
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