# 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

Live Demo

#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.

Updated on: 30-Dec-2020

1K+ Views

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