# Delete all Prime Nodes from a Singly Linked List

Given a singly linked list containing N nodes, the task is to delete all nodes from the list which are prime.

**Examples:**

Input :List = 15 -> 16 -> 6 -> 7 -> 17

Output :Final List = 15 -> 16 -> 6

Input :List = 15 -> 3 -> 4 -> 2 -> 9

Output :Final List = 15 ->4 -> 9

**Approach**: The idea is to traverse the nodes of the singly linked list one by one and get the pointer of the nodes which are prime. Delete those nodes by following the approach used in the post: Delete a node from Linked List.

Below is the implementation of above idea:

`// C++ implementation to delete all ` `// prime nodes from the singly ` `// linked list ` `#include <bits/stdc++.h> ` ` ` `using` `namespace` `std; ` ` ` `// Node of the singly linked list ` `struct` `Node { ` ` ` `int` `data; ` ` ` `Node* next; ` `}; ` ` ` `// function to insert a node at the beginning ` `// of the singly Linked List ` `void` `push(Node** head_ref, ` `int` `new_data) ` `{ ` ` ` `// allocate node ` ` ` `Node* new_node = (Node*)` `malloc` `(` `sizeof` `(` `struct` `Node)); ` ` ` ` ` `// put in the data ` ` ` `new_node->data = new_data; ` ` ` ` ` `// link the old list off the new node ` ` ` `new_node->next = (*head_ref); ` ` ` ` ` `// move the head to point to the new node ` ` ` `(*head_ref) = new_node; ` `} ` ` ` `// Function to check if a number is prime ` `bool` `isPrime(` `int` `n) ` `{ ` ` ` `// Corner cases ` ` ` `if` `(n <= 1) ` ` ` `return` `false` `; ` ` ` `if` `(n <= 3) ` ` ` `return` `true` `; ` ` ` ` ` `// This is checked so that we can skip ` ` ` `// middle five numbers in below loop ` ` ` `if` `(n % 2 == 0 || n % 3 == 0) ` ` ` `return` `false` `; ` ` ` ` ` `for` `(` `int` `i = 5; i * i <= n; i = i + 6) ` ` ` `if` `(n % i == 0 || n % (i + 2) == 0) ` ` ` `return` `false` `; ` ` ` ` ` `return` `true` `; ` `} ` ` ` `// function to delete a node in a singly Linked List. ` `// head_ref --> pointer to head node pointer. ` `// del --> pointer to node to be deleted ` `void` `deleteNode(Node** head_ref, Node* del) ` `{ ` ` ` `// base case ` ` ` `struct` `Node* temp = *head_ref; ` ` ` `if` `(*head_ref == NULL || del == NULL) ` ` ` `return` `; ` ` ` ` ` `// If node to be deleted is head node ` ` ` `if` `(*head_ref == del) ` ` ` `*head_ref = del->next; ` ` ` `// travers list till not found ` ` ` `// delete node ` ` ` `while` `(temp->next != del) { ` ` ` `temp = temp->next; ` ` ` `} ` ` ` `// copy address of node ` ` ` `temp->next = del->next; ` ` ` `// Finally, free the memory occupied by del ` ` ` `free` `(del); ` ` ` ` ` `return` `; ` `} ` ` ` `// function to delete all prime nodes ` `// from the singly linked list ` `void` `deletePrimeNodes(Node** head_ref) ` `{ ` ` ` `Node* ptr = *head_ref; ` ` ` `Node* next; ` ` ` ` ` `while` `(ptr != NULL) { ` ` ` `next = ptr->next; ` ` ` `// if true, delete node 'ptr' ` ` ` `if` `(isPrime(ptr->data)) ` ` ` `deleteNode(head_ref, ptr); ` ` ` `ptr = next; ` ` ` `} ` `} ` ` ` `// function to print nodes in a ` `// given singly linked list ` `void` `printList(Node* head) ` `{ ` ` ` `while` `(head != NULL) { ` ` ` `cout << head->data << ` `" "` `; ` ` ` `head = head->next; ` ` ` `} ` `} ` ` ` `// Driver program ` `int` `main() ` `{ ` ` ` `// start with the empty list ` ` ` `Node* head = NULL; ` ` ` ` ` `// create the linked list ` ` ` `// 15 -> 16 -> 7 -> 6 -> 17 ` ` ` `push(&head, 17); ` ` ` `push(&head, 7); ` ` ` `push(&head, 6); ` ` ` `push(&head, 16); ` ` ` `push(&head, 15); ` ` ` ` ` `cout << ` `"Original List: "` `; ` ` ` `printList(head); ` ` ` ` ` `deletePrimeNodes(&head); ` ` ` ` ` `cout << ` `"\nModified List: "` `; ` ` ` `printList(head); ` `} ` |

*chevron_right*

*filter_none*

**Output:**

Original List: 15 16 6 7 17 Modified List: 15 16 6

**Time Complexity: O(N)**, where N is the total number of nodes.

## Recommended Posts:

- Delete all Non-Prime Nodes from a Singly Linked List
- Delete all Prime Nodes from a Circular Singly Linked List
- Count of Prime Nodes of a Singly Linked List
- Sum and Product of all Prime Nodes of a Singly Linked List
- Delete all Prime Nodes from a Doubly Linked List
- Given only a pointer to a node to be deleted in a singly linked list, how do you delete it?
- Given only a pointer/reference to a node to be deleted in a singly linked list, how do you delete it?
- Sum of the nodes of a Singly Linked List
- Product of the nodes of a Singly Linked List
- Alternate Odd and Even Nodes in a Singly Linked List
- Sum and Product of the nodes of a Singly Linked List which are divisible by K
- Find the common nodes in two singly linked list
- Reverse alternate K nodes in a Singly Linked List
- Sum and Product of the nodes of a Circular Singly Linked List which are divisible by K
- Delete N nodes after M nodes of a linked list

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