# 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

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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++

 `// C++ implementation to delete all ` `// prime nodes from the singly ` `// linked list ` `#include ` ` `  `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; ` `    ``// traverse 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); ` `} `

## Java

 `// Java implementation to delete all  ` `// prime nodes from the singly  ` `// linked list  ` `class` `GFG ` `{ ` ` `  `// Node of the singly linked list  ` `static` `class` `Node  ` `{  ` `    ``int` `data;  ` `    ``Node next;  ` `};  ` ` `  `// function to insert a node at the beginning  ` `// of the singly Linked List  ` `static` `Node push(Node head_ref, ``int` `new_data)  ` `{  ` `    ``// allocate node  ` `    ``Node new_node = ``new` `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;  ` `    ``return` `head_ref; ` `}  ` ` `  `// Function to check if a number is prime  ` `static` `boolean` `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  ` `static` `Node deleteNode(Node head_ref, Node del)  ` `{  ` `    ``// base case  ` `    ``Node temp = head_ref;  ` `    ``if` `(head_ref == ``null` `|| del == ``null``)  ` `        ``return` `null``;  ` ` `  `    ``// If node to be deleted is head node  ` `    ``if` `(head_ref == del)  ` `        ``head_ref = del.next;  ` `         `  `    ``// traverse list till not found  ` `    ``// delete node  ` `    ``while` `(temp.next != del) ` `    ``{  ` `        ``temp = temp.next;  ` `    ``}  ` `     `  `    ``// copy address of node  ` `    ``temp.next = del.next;  ` `     `  ` `  `    ``return` `head_ref;  ` `}  ` ` `  `// function to delete all prime nodes  ` `// from the singly linked list  ` `static` `Node 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;  ` `    ``}  ` `    ``return` `head_ref; ` `}  ` ` `  `// function to print nodes in a  ` `// given singly linked list  ` `static` `void` `printList(Node head)  ` `{  ` `    ``while` `(head != ``null``) ` `    ``{  ` `        ``System.out.print( head.data + ``" "``);  ` `        ``head = head.next;  ` `    ``}  ` `}  ` ` `  `// Driver code  ` `public` `static` `void` `main(String args[]) ` `{  ` `    ``// start with the empty list  ` `    ``Node head = ``null``;  ` ` `  `    ``// create the linked list  ` `    ``// 15 . 16 . 7 . 6 . 17  ` `    ``head = push(head, ``17``);  ` `    ``head = push(head, ``7``);  ` `    ``head = push(head, ``6``);  ` `    ``head = push(head, ``16``);  ` `    ``head = push(head, ``15``);  ` ` `  `    ``System.out.print(``"Original List: "``);  ` `    ``printList(head);  ` ` `  `    ``head = deletePrimeNodes(head);  ` ` `  `    ``System.out.print(``"\nModified List: "``);  ` `    ``printList(head);  ` `}  ` `} ` ` `  `// This code is contributed by Arnab Kundu `

## Python3

 `# Python3 implementation to delete all ` `# prime nodes from the singly ` `# linked list ` ` `  `# Node class  ` `class` `Node:  ` ` `  `    ``# Constructor to initialize  ` `    ``# the node object  ` `    ``def` `__init__(``self``, data):  ` `        ``self``.data ``=` `data  ` `        ``self``.``next` `=` `None` ` `  `# function to insert a node at the beginning ` `# of the singly Linked List ` `def` `push(head_ref, new_data): ` ` `  `    ``# allocate node ` `    ``new_node ``=` `Node(``0``) ` ` `  `    ``# 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 ` `     `  `    ``return` `head_ref ` ` `  `# Function to check if a number is prime ` `def` `isPrime(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``) ``or` `(n ``%` `3` `=``=` `0``) : ` `        ``return` `False` `     `  `    ``i ``=` `6` `    ``while``( i ``*` `i <``=` `n ): ` `        ``if` `(n ``%` `i ``=``=` `0` `or` `n ``%` `(i ``+` `2``) ``=``=` `0``): ` `            ``return` `False` `        ``i ``=` `i ``+` `6` ` `  `    ``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 ` `def` `deleteNode(head_ref, del1): ` ` `  `    ``# base case ` `    ``temp ``=` `head_ref ` `    ``if` `(head_ref ``=``=` `None` `or` `del1 ``=``=` `None``): ` `        ``return` ` `  `    ``# If node to be deleted is head node ` `    ``if` `(head_ref ``=``=` `del1): ` `        ``head_ref ``=` `del1.``next` `         `  `    ``# traverse list till not found ` `    ``# delete node ` `    ``while` `(temp.``next` `!``=` `del1) : ` `        ``temp ``=` `temp.``next` `     `  `    ``# copy address of node ` `    ``temp.``next` `=` `del1.``next` `     `  `    ``return` `head_ref; ` ` `  `# function to delete all prime nodes ` `# from the singly linked list ` `def` `deletePrimeNodes(head_ref): ` ` `  `    ``ptr ``=` `head_ref ` `    ``next` `=` `None` ` `  `    ``while` `(ptr !``=` `None``) : ` `        ``next` `=` `ptr.``next` `         `  `        ``# if True, delete node 'ptr' ` `        ``if` `(isPrime(ptr.data)): ` `            ``head_ref ``=` `deleteNode(head_ref, ptr) ` `        ``ptr ``=` `next` `    ``return` `head_ref ` ` `  `# function to print nodes in a ` `# given singly linked list ` `def` `printList(head): ` ` `  `    ``while` `(head !``=` `None``) : ` `        ``print``(head.data, ``" "``, end ``=` `" "``) ` `        ``head ``=` `head.``next` `     `  `# Driver Code ` `if` `__name__``=``=``'__main__'``:  ` `     `  `    ``# start with the empty list ` `    ``head ``=` `None` ` `  `    ``# create the linked list ` `    ``# 15 . 16 . 7 . 6 . 17 ` `    ``head ``=` `push(head, ``17``) ` `    ``head ``=` `push(head, ``7``) ` `    ``head ``=` `push(head, ``6``) ` `    ``head ``=` `push(head, ``16``) ` `    ``head ``=` `push(head, ``15``) ` ` `  `    ``print``( ``"Original List: "``) ` `    ``printList(head) ` ` `  `    ``head ``=` `deletePrimeNodes(head) ` ` `  `    ``print``(``"\nModified List: "``) ` `    ``printList(head) ` `     `  `# This code is contributed by Arnab Kundu `

## C#

 `// C# implementation to delete all  ` `// prime nodes from the singly  ` `// linked list  ` `using` `System; ` ` `  `class` `GFG  ` `{  ` ` `  `// Node of the singly linked list  ` `public` `class` `Node  ` `{  ` `    ``public` `int` `data;  ` `    ``public` `Node next;  ` `};  ` ` `  `// function to insert a node at the beginning  ` `// of the singly Linked List  ` `static` `Node push(Node head_ref, ``int` `new_data)  ` `{  ` `    ``// allocate node  ` `    ``Node new_node = ``new` `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;  ` `    ``return` `head_ref;  ` `}  ` ` `  `// Function to check if a number is prime  ` `static` `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  ` `static` `Node deleteNode(Node head_ref, Node del)  ` `{  ` `    ``// base case  ` `    ``Node temp = head_ref;  ` `    ``if` `(head_ref == ``null` `|| del == ``null``)  ` `        ``return` `null``;  ` ` `  `    ``// If node to be deleted is head node  ` `    ``if` `(head_ref == del)  ` `        ``head_ref = del.next;  ` `         `  `    ``// traverse list till not found  ` `    ``// delete node  ` `    ``while` `(temp.next != del)  ` `    ``{  ` `        ``temp = temp.next;  ` `    ``}  ` `     `  `    ``// copy address of node  ` `    ``temp.next = del.next;  ` `     `  ` `  `    ``return` `head_ref;  ` `}  ` ` `  `// function to delete all prime nodes  ` `// from the singly linked list  ` `static` `Node 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;  ` `    ``}  ` `    ``return` `head_ref;  ` `}  ` ` `  `// function to print nodes in a  ` `// given singly linked list  ` `static` `void` `printList(Node head)  ` `{  ` `    ``while` `(head != ``null``)  ` `    ``{  ` `        ``Console.Write( head.data + ``" "``);  ` `        ``head = head.next;  ` `    ``}  ` `}  ` ` `  `// Driver code  ` `public` `static` `void` `Main()  ` `{  ` `    ``// start with the empty list  ` `    ``Node head = ``null``;  ` ` `  `    ``// create the linked list  ` `    ``// 15 . 16 . 7 . 6 . 17  ` `    ``head = push(head, 17);  ` `    ``head = push(head, 7);  ` `    ``head = push(head, 6);  ` `    ``head = push(head, 16);  ` `    ``head = push(head, 15);  ` ` `  `    ``Console.Write(``"Original List: "``);  ` `    ``printList(head);  ` ` `  `    ``head = deletePrimeNodes(head);  ` ` `  `    ``Console.Write(``"\nModified List: "``);  ` `    ``printList(head);  ` `}  ` `}  ` ` `  `// This code is contributed by Princi Singh `

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.

My Personal Notes arrow_drop_up Strategy Path planning and Destination matters in success No need to worry about in between temporary failures

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