Delete all Prime Nodes from a Circular Singly Linked List

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

Examples:



Input : 9->11->32->6->13->20 
Output : Given List : 9 11 32 6 13 20 
List After delete prime node : 9 32 6 20 

Input : 6->11->16->21->17->10 
Output : Given List : 6 11 16 21 17 10
List After delete prime node : 10 21 16 6 

Approach: The idea is to traverse the nodes of the circular 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 circular Linked List.

Below is the implementation of the above idea:

C++

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// CPP program to delete all prime
// node from a Circular singly linked list
  
#include <bits/stdc++.h>
using namespace std;
  
// Structure for a node
struct Node {
    int data;
    struct Node* next;
};
  
// Function to insert a node at the beginning
// of a Circular linked list
void push(struct Node** head_ref, int data)
{
    struct Node* ptr1 = (struct Node*)malloc(sizeof(struct Node));
    struct Node* temp = *head_ref;
    ptr1->data = data;
    ptr1->next = *head_ref;
  
    // If linked list is not NULL then
    // set the next of last node
    if (*head_ref != NULL) {
        while (temp->next != *head_ref)
            temp = temp->next;
        temp->next = ptr1;
    }
    else
        ptr1->next = ptr1; // For the first node
  
    *head_ref = ptr1;
}
  
// Delete the node if it is prime
void deleteNode(Node* head_ref, Node* del)
{
    struct Node* temp = head_ref;
    // 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 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 all prime nodes
// from the singly circular linked list
void deletePrimeNodes(Node* head)
{
    struct Node* ptr = head;
  
    struct Node* next;
  
    // traverse list till the endl
    // if node is prime then delete it
    do {
        // if node is prime
        if (isPrime(ptr->data))
            deleteNode(head, ptr);
  
        // point to next node
        next = ptr->next;
        ptr = next;
  
    } while (ptr != head);
}
  
// Function to print nodes in a
// given singly linked list
void printList(struct Node* head)
{
    struct Node* temp = head;
    if (head != NULL) {
        do {
            printf("%d ", temp->data);
            temp = temp->next;
        } while (temp != head);
    }
}
  
// Driver code
int main()
{
    // Initialize lists as empty
    struct Node* head = NULL;
  
    // Created linked list will be
    // 9->11->32->6->13->20
    push(&head, 20);
    push(&head, 13);
    push(&head, 6);
    push(&head, 32);
    push(&head, 11);
    push(&head, 9);
  
    cout << "Given List : ";
    printList(head);
  
    cout << "\nList After deleting prime nodes : ";
    deletePrimeNodes(head);
    printList(head);
  
    return 0;
}

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Java

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// Java program to delete all prime 
// node from a Circular singly linked list 
class GFG
{
      
// Structure for a node 
static class Node 
    int data; 
    Node next; 
}; 
  
// Function to insert a node at the beginning 
// of a Circular linked list 
static Node push(Node head_ref, int data) 
    Node ptr1 = new Node(); 
    Node temp = head_ref; 
    ptr1.data = data; 
    ptr1.next = head_ref; 
  
    // If linked list is not null then 
    // set the next of last node 
    if (head_ref != null
    
        while (temp.next != head_ref) 
            temp = temp.next; 
        temp.next = ptr1; 
    
    else
        ptr1.next = ptr1; // For the first node 
  
    head_ref = ptr1;
    return head_ref;
  
// Delete the node if it is prime 
static Node deleteNode(Node head_ref, Node del) 
    Node temp = head_ref; 
  
    // 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 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 all prime nodes 
// from the singly circular linked list 
static Node deletePrimeNodes(Node head) 
    Node ptr = head; 
  
    Node next; 
  
    // traverse list till the endl 
    // if node is prime then delete it 
    do 
    
        // if node is prime 
        if (isPrime(ptr.data)) 
            deleteNode(head, ptr); 
  
        // point to next node 
        next = ptr.next; 
        ptr = next; 
  
    
    while (ptr != head); 
        return head;
  
// Function to print nodes in a 
// given singly linked list 
static void printList(Node head) 
    Node temp = head; 
    if (head != null
    
        do
        
            System.out.printf("%d ", temp.data); 
            temp = temp.next; 
        
        while (temp != head); 
    
  
// Driver code 
public static void main(String args[]) 
    // Initialize lists as empty 
    Node head = null
  
    // Created linked list will be 
    // 9.11.32.6.13.20 
    head=push(head, 20); 
    head=push(head, 13); 
    head=push(head, 6); 
    head=push(head, 32); 
    head=push(head, 11); 
    head=push(head, 9); 
  
    System.out.println("Given List : "); 
    printList(head); 
  
    System.out.println( "\nList After deleting prime nodes : "); 
    head=deletePrimeNodes(head); 
    printList(head); 
}
  
// This code is contributed by Arnab Kundu

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C#

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// C# program to delete all prime 
// node from a Circular singly linked list
using System;
  
class GFG
{
      
// Structure for a node 
public class Node 
    public int data; 
    public Node next; 
}; 
  
// Function to insert a node at the beginning 
// of a Circular linked list 
static Node push(Node head_ref, int data) 
    Node ptr1 = new Node(); 
    Node temp = head_ref; 
    ptr1.data = data; 
    ptr1.next = head_ref; 
  
    // If linked list is not null then 
    // set the next of last node 
    if (head_ref != null
    
        while (temp.next != head_ref) 
            temp = temp.next; 
        temp.next = ptr1; 
    
    else
        ptr1.next = ptr1; // For the first node 
  
    head_ref = ptr1;
    return head_ref;
  
// Delete the node if it is prime 
static Node deleteNode(Node head_ref, Node del) 
    Node temp = head_ref; 
  
    // 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 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 all prime nodes 
// from the singly circular linked list 
static Node deletePrimeNodes(Node head) 
    Node ptr = head; 
  
    Node next; 
  
    // traverse list till the endl 
    // if node is prime then delete it 
    do
    
        // if node is prime 
        if (isPrime(ptr.data)) 
            deleteNode(head, ptr); 
  
        // point to next node 
        next = ptr.next; 
        ptr = next; 
  
    
    while (ptr != head); 
        return head;
  
// Function to print nodes in a 
// given singly linked list 
static void printList(Node head) 
    Node temp = head; 
    if (head != null
    
        do
        
            Console.Write("{0} ", temp.data); 
            temp = temp.next; 
        
        while (temp != head); 
    
  
// Driver code 
public static void Main() 
    // Initialize lists as empty 
    Node head = null
  
    // Created linked list will be 
    // 9.11.32.6.13.20 
    head=push(head, 20); 
    head=push(head, 13); 
    head=push(head, 6); 
    head=push(head, 32); 
    head=push(head, 11); 
    head=push(head, 9); 
  
    Console.WriteLine("Given List : "); 
    printList(head); 
  
    Console.WriteLine( "\nList After deleting prime nodes : "); 
    head=deletePrimeNodes(head); 
    printList(head); 
  
/* This code contributed by PrinciRaj1992 */

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Output:

Given List : 9 11 32 6 13 20 
List After deleting prime nodes : 9 32 6 20


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