Delete all Prime Nodes from a Circular Singly Linked List

Last Updated : 06 Sep, 2022

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 : 9 32 6 20

Input : 6->11->16->21->17->10
Output : 6 16 21 10

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++

// 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, *temp2 = head_ref;
    // 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
Node* deletePrimeNodes(Node* head)
{
   if (head == NULL)
        return NULL;
    struct Node* ptr = head;

    struct Node* temp;

    // setting up the head node to the first non prime node
    while (isPrime(ptr->data)) {
        ptr = ptr->next;
        if (ptr == head) {
            return NULL;
        }
    }
    temp = ptr;
    Node* temp2 = ptr;
    ptr = ptr->next;
    // setting up the last node next to the first non prime
    // node
    while (ptr != head) {
        temp2 = ptr;
        ptr = ptr->next;
    }
    temp2->next = temp;
    head = temp;
    ptr = head;
    // traverse list till the endl
    // if node is prime then delete it
    do {
        temp = ptr->next;
        // if node is prime
        if (isPrime(ptr->data))
            deleteNode(head, ptr);
        ptr = temp;

    } while (ptr != head);
    return head;
}

// Function to print nodes in a
// given singly linked list
void printList(struct Node* head)
{
    if (!head) {
        printf("NULL");
    }
    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 : ";
    head = deletePrimeNodes(head);
    printList(head);

    return 0;
}

Java

// 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

Python3

# Python3 program to delete all prime
# node from a Circular singly linked list
import math 

# Structure for a node
class Node: 
    def __init__(self, data): 
        self.data = data 
        self.next = None

# Function to insert a node at the 
# beginning of a Circular linked list
def push(head_ref, data):
    ptr1 = Node(data)
    temp = head_ref
    ptr1.data = data
    ptr1.next = head_ref

    # If linked list is not None then
    # set the next of last node
    if (head_ref != None) :
        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
def deleteNode(head_ref, delete):
    temp = head_ref
    
    # If node to be deleted is head node
    if (head_ref == delete):
        head_ref = delete.next

    # traverse list till not found
    # delete node
    while (temp.next != delete):
        temp = temp.next
    
    # copy address of node
    temp.next = delete.next

    # Finally, free the memory
    # occupied by delete
    # free(delete)
    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

    for i in range(5, n + 1, 6):
        if (i * i < n + 2 and 
               (n % i == 0 or 
                n % (i + 2) == 0)):
            return False

    return True

# Function to delete all prime nodes
# from the singly circular linked list
def deletePrimeNodes( head):
    ptr = head

    #next

    # traverse list till the endl
    # if node is prime then delete it
    # if (isPrime(ptr.data)!=True):
    # deleteNode(head, ptr)

    # point to next node
    next = ptr.next
    ptr = next
    while (ptr != head):
        
        # if node is prime
        if (isPrime(ptr.data) == True):
            deleteNode(head, ptr)

        # point to next node
        next = ptr.next
        ptr = next

    return head 

# Function to print nodes in a
# given singly linked list
def printList(head):
    temp = head
    if (head != None) :
        print(temp.data, end = " ")
        temp = temp.next
        while (temp != head):
            print(temp.data, end = " ")
            temp = temp.next
    
# Driver code
if __name__=='__main__': 

    # Initialize lists as empty
    head = None

    # 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)

    print("Given List : ", end = "")
    printList(head)

    print( "\nList After deleting", 
           "prime nodes : ", end = "")
    head = deletePrimeNodes(head)
    printList(head)

# This code is contributed by Srathore

// 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 */

JavaScript

<script>

// JavaScript program to delete all prime 
// node from a Circular singly linked list 

// Structure for a node
class Node {
    constructor() {
        this.data = 0;
        this.next = null;
    }
}

    // Function to insert a node at the beginning
    // of a Circular linked list
    function push(head_ref , data) {
    var ptr1 = new Node();
    var 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
    function deleteNode(head_ref,  del) {
    var 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
    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 all prime nodes
    // from the singly circular linked list
    function deletePrimeNodes(head) {
    var ptr = head;

    var 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
    function printList(head) {
    var temp = head;
        if (head != null) {
            do {
                document.write( temp.data+" ");
                temp = temp.next;
            } while (temp != head);
        }
    }

    // Driver code
    
        // Initialize lists as empty
    var 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);

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

        document.write(
        "<br/>List After deleting prime nodes : <br/>"
        );
        head = deletePrimeNodes(head);
        printList(head);

// This code contributed by aashish1995 

</script>

Output

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

Complexity Analysis:

Time Complexity: O(N * sqrt(N))
Auxiliary Space: O(1)

Remove all the Even Digit Sum Nodes from a Circular Singly Linked List

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Delete all Prime Nodes from a Circular Singly Linked List

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