检查给定链表的长度是偶数还是奇数
原文：https://www.geeksforgeeks.org/check-whether-the-length-of-given-linked-list-is-even-or-odd/
给定一个链表，任务是创建一个函数来检查链表的长度是偶数还是奇数。
示例：
Input : 1->2->3->4->NULL
Output : Even
Input : 1->2->3->4->5->NULL
Output : Odd
方法 1：线性计算代码
遍历整个链表，并继续计算节点数。 循环结束后，我们可以检查计数是偶数还是奇数。 您可以自己尝试。
方法 2：一次步进 2 个节点
方法：
1\. Take a pointer and move that pointer two nodes at a time
2\. At the end, if the pointer is NULL then length is Even, else Odd.
C++
// C++ program to check length
// of a given linklist
#include <bits/stdc++.h>
using namespace std;
// Defining structure
class Node
{
public:
int data;
Node* next;
};
// Function to check the length of linklist
int LinkedListLength(Node* head)
{
while (head && head->next)
{
head = head->next->next;
}
if (!head)
return 0;
return 1;
}
// Push function
void push(Node** head, int info)
{
// Allocating node
Node* node = new Node();
// Info into node
node->data = info;
// Next of new node to head
node->next = (*head);
// head points to new node
(*head) = node;
}
// Driver code
int main(void)
{
Node* head = NULL;
// Adding elements to Linked List
push(&head, 4);
push(&head, 5);
push(&head, 7);
push(&head, 2);
push(&head, 9);
push(&head, 6);
push(&head, 1);
push(&head, 2);
push(&head, 0);
push(&head, 5);
push(&head, 5);
int check = LinkedListLength(head);
// Checking for length of
// linklist
if(check == 0)
{
cout << "Even\n";
}
else
{
cout << "Odd\n";
}
return 0;
}
// This is code is contributed by rathbhupendra
C
// C program to check length
// of a given linklist
#include<stdio.h>
#include<stdlib.h>
// Defining structure
struct Node
{
int data;
struct Node* next;
};
// Function to check the length of linklist
int LinkedListLength(struct Node* head)
{
while (head && head->next)
{
head = head->next->next;
}
if (!head)
return 0;
return 1;
}
// Push function
void push(struct Node** head, int info)
{
// Allocating node
struct Node* node = (struct Node*) malloc(sizeof(struct Node));
// Info into node
node->data = info;
// Next of new node to head
node->next = (*head);
// head points to new node
(*head) = node;
}
// Driver function
int main(void)
{
struct Node* head = NULL;
// Adding elements to Linked List
push(&head, 4);
push(&head, 5);
push(&head, 7);
push(&head, 2);
push(&head, 9);
push(&head, 6);
push(&head, 1);
push(&head, 2);
push(&head, 0);
push(&head, 5);
push(&head, 5);
int check = LinkedListLength(head);
// Checking for length of
// linklist
if(check == 0)
{
printf("Even\n");
}
else
{
printf("Odd\n");
}
return 0;
}
Java
/*package whatever //do not write package name here */
import java.io.*;
// Java program to check length
// of a given linklist
class GfG
{
// Defining structure
static class Node
{
int data;
Node next;
}
// Function to check the length of linklist
static int LinkedListLength(Node head)
{
while (head != null && head.next != null)
{
head = head.next.next;
}
if (head == null)
return 0;
return 1;
}
// Push function
static void push(Node head, int info)
{
// Allocating node
Node node = new Node();
// Info into node
node.data = info;
// Next of new node to head
node.next = (head);
// head points to new node
(head) = node;
}
// Driver code
public static void main(String[] args)
{
Node head = null;
// Adding elements to Linked List
push(head, 4);
push(head, 5);
push(head, 7);
push(head, 2);
push(head, 9);
push(head, 6);
push(head, 1);
push(head, 2);
push(head, 0);
push(head, 5);
push(head, 5);
int check = LinkedListLength(head);
// Checking for length of
// linklist
if(check == 0)
{
System.out.println("Odd");
}
else
{
System.out.println("Even");
}
}
}
// This code is contributed by Prerna saini
Python3
# Python program to check length
# of a given linklist
# Defining structure
class Node:
def __init__(self, d):
self.data = d
self.next = None
self.head = None
# Function to check the length of linklist
def LinkedListLength(self):
while (self.head != None and self.head.next != None):
self.head = self.head.next.next
if(self.head == None):
return 0
return 1
# Push function
def push(self, info):
# Allocating node
node = Node(info)
# Next of new node to head
node.next = (self.head)
# head points to new node
(self.head) = node
# Driver code
head = Node(0)
# Adding elements to Linked List
head.push( 4)
head.push( 5)
head.push( 7)
head.push( 2)
head.push( 9)
head.push( 6)
head.push( 1)
head.push( 2)
head.push( 0)
head.push( 5)
head.push( 5)
check = head.LinkedListLength()
# Checking for length of
# linklist
if(check == 0) :
print("Even")
else:
print("Odd")
# This code is contributed by Prerna saini
C
// C# program to check length
// of a given linklist
using System;
class GfG
{
// Defining structure
class Node
{
public int data;
public Node next;
}
// Function to check the length of linklist
static int LinkedListLength(Node head)
{
while (head != null && head.next != null)
{
head = head.next.next;
}
if (head == null)
return 0;
return 1;
}
// Push function
static void push(Node head, int info)
{
// Allocating node
Node node = new Node();
// Info into node
node.data = info;
// Next of new node to head
node.next = (head);
// head points to new node
(head) = node;
}
// Driver code
public static void Main()
{
Node head = null;
// Adding elements to Linked List
push(head, 4);
push(head, 5);
push(head, 7);
push(head, 2);
push(head, 9);
push(head, 6);
push(head, 1);
push(head, 2);
push(head, 0);
push(head, 5);
push(head, 5);
int check = LinkedListLength(head);
// Checking for length of
// linklist
if(check == 0)
{
Console.WriteLine("Odd");
}
else
{
Console.WriteLine("Even");
}
}
}
// This code has been contributed
// by PrinciRaj1992
输出：
Odd
时间复杂度：O(n)
空间复杂度：O(1)
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