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Delete all Prime Nodes from a Singly Linked List

  • Difficulty Level : Easy
  • Last Updated : 21 May, 2021

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++




// 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;
    // 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

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 off the new node
        new_node.next = (head_ref);
 
        // move the head to povar 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 prvar 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: 15 16 6 7 17 
Modified List: 15 16 6

 

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

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