Delete alternate nodes of a Linked List in C++

In this tutorial, we are going to learn how to delete all prime nodes from a singly linked list.

Let's see the steps to solve the problem.

Write struct with data and next pointer.
Write a function to insert the node into the singly linked list.
Initialize the singly linked list with dummy data.
Iterate over the singly linked list.
Delete alternate node by maintaining the previous node.
Write a function to delete the node. Consider the following three cases while deleting the node.
- If the node is head node, then move the head to next node.
- If the node is middle node, then link the next node to the previous node
- If the node is end node, then remove the previous node link. Let's see the code.

Example

#include <bits/stdc++.h>
using namespace std;
struct Node {
   int data;
   Node *next;
};
void deleteAlternateNodes(Node *head) {
   if (head == NULL)
      return;
   Node *prev = head;
   Node *node = head->next;
   while (prev != NULL && node != NULL) {
      prev->next = node->next;
      free(node);
      prev = prev->next;
      if (prev != NULL) {
         node = prev->next;
      }
   }
}
void insertNode(Node** head_ref, int new_data) {
   Node* new_node = new Node();
   new_node->data = new_data;
   new_node->next = (*head_ref);
   (*head_ref) = new_node;
}
void printLinkedList(Node *node) {
   while (node != NULL) {
      cout << node->data << " -> ";
      node = node->next;
   }
}
int main() {
   Node* head = NULL;
   insertNode(&head, 1);
   insertNode(&head, 2);
   insertNode(&head, 3);
   insertNode(&head, 4);
   insertNode(&head, 5);
   insertNode(&head, 6);
   cout << "Linked List before deletion:" << endl;
   printLinkedList(head);
   deleteAlternateNodes(head);
   cout << "\nLinked List after deletion:" << endl;
   printLinkedList(head);
   return 0;
}

Output

If you execute the above program, then you will get the following result.

Linked List before deletion:
6 -> 5 -> 4 -> 3 -> 2 -> 1 ->
Linked List after deletion:
6 -> 4 -> 2 ->

Conclusion

If you have any queries in the tutorial, mention them in the comment section.

Hafeezul Kareem

Published on 30-Dec-2020 07:01:00

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