Check whether the length of given linked list is Even or Odd
Given a linked list, the task is to make a function which checks whether the length of the linked list is even or odd.
Examples:
Input : 1->2->3->4->NULL Output : Even Input : 1->2->3->4->5->NULL Output : Odd
Method 1: Count the codes linearly
Traverse the entire Linked List and keep counting the number of nodes. As soon as the loop is finished, we can check if the count is even or odd. You may try it yourself.
Method 2: Stepping 2 nodes at a time
Approach:
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.
Implementation:
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 |
Javascript
<script> // JavaScript program to check length // of a given linklist // Defining structure class Node { constructor() { this .data = 0; this .next = null ; } } // Function to check the length of linklist function LinkedListLength( head) { while (head != null && head.next != null ) { head = head.next.next; } if (head == null ) return 0; return 1; } // Push function function push( head , info) { // Allocating 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 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); var check = LinkedListLength(head); // Checking for length of // linklist if (check == 0) { document.write( "Odd" ); } else { document.write( "Even" ); } // This code contributed by umadevi9616 </script> |
Output
Odd
Time Complexity: O(n)
Space Complexity: O(1)
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