C Exercises: Delete alternate nodes of a singly linked list

Last update on December 20 2024 13:06:19 (UTC/GMT +8 hours)

Write a C program to delete alternate nodes of a singly linked list.

Sample Solution:

C Code:

#include<stdio.h>
#include<stdlib.h>

// Structure defining a node in a singly linked list
struct Node {
    int data;           // Data stored in the node
    struct Node *next;  // Pointer to the next node
};

// Function to create a new node in the singly linked list
struct Node *newNode(int data) {
    struct Node *temp = (struct Node *) malloc(sizeof(struct Node));  // Allocate memory for a new node
    temp->data = data;  // Assign data to the new node
    temp->next = NULL;  // Initialize the next pointer as NULL
    return temp;  // Return the new node
}

// Function to print the elements of the linked list
void printList(struct Node *head) {
    while (head != NULL) {
        printf("%d ", head->data);  // Print the data of the current node
        head = head->next;  // Move to the next node
    }
    printf("\n");
}

// Function to delete alternate nodes in a singly linked list
void delete_Alternate_Nodes(struct Node** head) {
    if (*head == NULL) return;  // If the list is empty, return

    struct Node* prev = *head;  // Pointer to the current node
    struct Node* curr = (*head)->next;  // Pointer to the next node

    while (curr != NULL) {
        prev->next = curr->next;  // Adjust the next pointer of the previous node
        free(curr);  // Free the memory of the current node
        prev = prev->next;  // Move to the next node (every alternate node)
        if (prev != NULL)
            curr = prev->next;  // Move to the node after the next node
    }
}

int main() {
    struct Node *head = newNode(1);  // Create a linked list
    head->next = newNode(2);
    head->next->next = newNode(3);
    head->next->next->next = newNode(4);
    head->next->next->next->next = newNode(5);
    head->next->next->next->next->next = newNode(6);
    head->next->next->next->next->next->next = newNode(7);

    printf("Original List:\n");
    printList(head);

    delete_Alternate_Nodes(&head);  // Delete alternate nodes in the list
    printf("\nDelete alternate nodes of the said singly linked list:\n");
    printList(head);

    return 0;
}

Sample Output:

Original List:
1 2 3 4 5 6 7 

Delete alternate nodes of the said singly linked list:
1 3 5 7

Flowchart :

C Programming Code Editor:

Previous: Split a singly linked list into two halves.
Next: Merge alternate nodes of two linked lists.