C Program To 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.
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 code 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" ); } else { printf ( "Odd" ); } return 0; } |
Output:
Odd
Time Complexity: O(n)
Auxiliary Space: O(1)
Using Recursion
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) { if (head == NULL) return 0; return 1+LinkedListLength(head->next); } // 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 code 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" ); } else { printf ( "Odd" ); } return 0; } //This code is contributed Vinay Pinjala. |
Output
Odd
Time Complexity: O(n)
Auxiliary Space: O(n)
Please refer complete article on Check whether the length of given linked list is Even or Odd for more details!
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