Delete all Prime Nodes from a Singly Linked List

Last Updated : 03 Mar, 2023

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 the above idea:

C++

// 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 of 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;
          return;
    }
    // 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, 5);

    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

import java.util.*;

// Node of the singly linked list
class Node {
    int data;
    Node next;
}
class GFG {
    // function to insert a node at the beginning
    // of the singly Linked List
    static void 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 of the new node
        new_node.next = head_ref[0];
        
         // move the head to point to the new node
        head_ref[0] = new_node;
    }
    
    // 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 void deleteNode(Node head_ref[], Node del) {
        
        // base case
        if (head_ref[0] == null || del == null)
            return;
            
           // If node to be deleted is head node
        if (head_ref[0] == del) {
            head_ref[0] = del.next;
            return;
        }
        
        // traverse list till not found
        // delete node
        Node temp = head_ref[0];
        while (temp.next != del) {
            temp = temp.next;
        }
        // copy address of node
        temp.next = del.next;
        
        // Finally, free the memory occupied by del
        del = null;
    }
    
    // function to delete all prime nodes
    // from the singly linked list
    static void deletePrimeNodes(Node head_ref[]) {
        Node ptr = head_ref[0];
        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
    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_ref = new Node[1];
        head_ref[0] = null;

        // create the linked list
        // 15 -> 16 -> 7 -> 6 -> 17
        push(head_ref, 17);
        push(head_ref, 7);
        push(head_ref, 6);
        push(head_ref, 16);
        push(head_ref, 5);

        System.out.print("Original List: ");
        printList(head_ref[0]);

        deletePrimeNodes(head_ref);

        System.out.print("\nModified List: ");
        printList(head_ref[0]);
    }
}

// this code is contributed by bhardwajji

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 of 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# 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 of 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

JavaScript

<script>
// javascript implementation to delete all 
// prime nodes from the singly 
// linked list     // Node of the singly linked list
class Node {
    constructor() {
        this.data = 0;
        this.next = null;
    }
}

    // function to insert a node at the beginning
    // of the singly Linked List
    function push(head_ref , new_data) {
        // allocate node
var new_node = new Node();

        // put in the data
        new_node.data = new_data;

        // link the old list of 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
    function 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 || n % 3 == 0)
            return false;

        for (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
    function deleteNode(head_ref,  del) {
        // base case
var 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
    function deletePrimeNodes(head_ref) {
var ptr = head_ref;
var 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
    function printList(head) {
        while (head != null) {
            document.write(head.data + " ");
            head = head.next;
        }
    }

    // Driver code
    
        // start with the empty list
var 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);

        document.write("Original List: ");
        printList(head);

        head = deletePrimeNodes(head);

        document.write("<br/>Modified List: ");
        printList(head);

// This code contributed by aashish1995 
</script>

Output

Original List: 5 16 6 7 17 
Modified List: 16 6

Time Complexity: O(N), where N is the total number of nodes.
Auxiliary Space: O(1)

Delete all Prime Nodes from a Singly Linked List

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Delete all Prime Nodes from a Singly Linked List

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