Skip to content
Related Articles

Related Articles

Improve Article
Remove all the Even Digit Sum Nodes from a Circular Singly Linked List
  • Difficulty Level : Basic
  • Last Updated : 21 May, 2021

Given a circular singly linked list containing N nodes, the task is to remove all the nodes from the list which contains elements whose digit sum is even.

Examples:

Input: CLL = 9 -> 11 -> 34 -> 6 -> 13 -> 21 
Output: 9 -> 34 -> 21 
Explanation: 
The circular singly linked list contains : 
9 -> 9 
11 -> 1 + 1 = 2 
34 -> 3 + 4 = 7 
6 -> 6 
13 -> 1 + 3 = 4 
21 -> 2 + 1 = 3 
Here, digit sum for nodes containing 11, 6 and 13 are even. 
Hence, these nodes have been deleted.

Input: 5 -> 11 -> 16 -> 21 -> 17 -> 10 
Output: 5 -> 16 -> 21 -> 10 
Explanation: 
The linked list contains two digit sum values 11 and 17. 
Hence, these nodes have been deleted.

Approach: The idea is to traverse the nodes of the circular singly linked list one by one and for each node, find the digit sum for the value present in the node by iterating through each digit. If the digit sum is even, then remove the nodes. Else, continue.



Below is the implementation of the above approach:

C++




// C++ program to remove all
// the Even Digit Sum Nodes 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)
{
    // Create a new node and make head as next
    // of it.
    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) {
 
        // Find the node before head
        // and update next of it.
        while (temp->next != *head_ref)
            temp = temp->next;
 
        temp->next = ptr1;
    }
    else
 
        // Point for the first node
        ptr1->next = ptr1;
 
    *head_ref = ptr1;
}
 
// Function to delete the node from a
// Circular Linked list
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 the address of the node
    temp->next = del->next;
 
    // Finally, free the memory
    // occupied by del
    free(del);
 
    return;
}
 
// Function to find the digit sum
// for a number
int digitSum(int num)
{
    int sum = 0;
    while (num) {
        sum += (num % 10);
        num /= 10;
    }
 
    return sum;
}
 
// Function to delete all the Even Digit Sum Nodes
// from the singly circular linked list
void deleteEvenDigitSumNodes(Node* head)
{
    struct Node* ptr = head;
 
    struct Node* next;
 
    // Traverse the list till the end
    do {
 
        // If the node's data is Fibonacci,
        // delete node 'ptr'
        if (!(digitSum(ptr->data) & 1))
            deleteNode(head, ptr);
 
        // Point to the next node
        next = ptr->next;
        ptr = next;
 
    } while (ptr != head);
}
 
// Function to print nodes in a
// given Circular 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->34->6->13->21
    push(&head, 21);
    push(&head, 13);
    push(&head, 6);
    push(&head, 34);
    push(&head, 11);
    push(&head, 9);
 
    deleteEvenDigitSumNodes(head);
 
    printList(head);
 
    return 0;
}

Java




// Java program to remove all
// the Even Digit Sum Nodes from a
// circular singly linked list
import java.util.*;
  
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)
{
     
    // Create a new node and make head
    // as next of it.
    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)
    {
  
        // Find the node before head
        // and update next of it.
        while (temp.next != head_ref)
            temp = temp.next;
  
        temp.next = ptr1;
    }
    else
  
        // Point for the first node
        ptr1.next = ptr1;
  
    head_ref = ptr1;
    return head_ref;
}
  
// Function to delete the node from a
// Circular Linked list
static void 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 the address of the node
    temp.next = del.next;
  
    // Finally, free the memory
    // occupied by del
    del = null;
  
    return;
}
  
// Function to find the digit sum
// for a number
static int digitSum(int num)
{
    int sum = 0;
     
    while (num > 0)
    {
        sum += (num % 10);
        num /= 10;
    }
    return sum;
}
  
// Function to delete all the Even Digit
// Sum Nodes from the singly circular
// linked list
static void deleteEvenDigitSumNodes(Node head)
{
    Node ptr = head;
    Node next;
  
    // Traverse the list till the end
    do
    {
         
        // If the node's data is Fibonacci,
        // delete node 'ptr'
        if (!(digitSum(ptr.data) % 2 == 1))
            deleteNode(head, ptr);
  
        // Point to the next node
        next = ptr.next;
        ptr = next;
    } while (ptr != head);
}
  
// Function to print nodes in a
// given Circular 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
    // 9.11.34.6.13.21
    head = push(head, 21);
    head = push(head, 13);
    head = push(head, 6);
    head = push(head, 34);
    head = push(head, 11);
    head = push(head, 9);
  
    deleteEvenDigitSumNodes(head);
  
    printList(head);
}
}
  
// This code is contributed by Amit Katiyar

Python3




# Python3 program to remove all
# the Even Digit Sum Nodes from a
# circular singly linked list
  
# 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):
     
    # Create a new node and make head as next
    # of it.
    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):
  
        # Find the node before head
        # and update next of it.
        while (temp.next != head_ref):
            temp = temp.next
  
        temp.next = ptr1
     
    else:
  
        # Point for the first node
        ptr1.next = ptr1
  
    head_ref = ptr1
     
    return head_ref
 
# Function to deltete the node from a
# Circular Linked list
def delteteNode(head_ref, delt):
 
    temp = head_ref
  
    # If node to be delteted is head node
    if (head_ref == delt):
        head_ref = delt.next
  
    # Traverse list till not found
    # deltete node
    while (temp.next != delt):
        temp = temp.next
  
    # Copy the address of the node
    temp.next = delt.next
  
    # Finally, free the memory
    # occupied by delt
    del (delt)
  
    return
 
# Function to find the digit sum
# for a number
def digitSum(num):
 
    sum = 0
     
    while (num != 0):
        sum += (num % 10)
        num //= 10
     
    return sum
 
# Function to deltete all the Even Digit
# Sum Nodes from the singly circular linked list
def delteteEvenDigitSumNodes(head):
 
    ptr = head
    next = None
  
    # Traverse the list till the end
    while True:
         
        # If the node's data is Fibonacci,
        # deltete node 'ptr'
        if (not (digitSum(ptr.data) & 1)):
            delteteNode(head, ptr)
  
        # Point to the next node
        next = ptr.next
        ptr = next
         
        if (ptr == head):
            break
     
# Function to print nodes in a
# given Circular linked list
def printList(head):
 
    temp = head
     
    if (head != None):
        while True:
            print(temp.data, end = ' ')
            temp = temp.next
             
            if (temp == head):
                break
         
# Driver code
if __name__=='__main__':
     
    # Initialize lists as empty
    head = None
  
    # Created linked list will be
    # 9.11.34.6.13.21
    head = push(head, 21)
    head = push(head, 13)
    head = push(head, 6)
    head = push(head, 34)
    head = push(head, 11)
    head = push(head, 9)
  
    delteteEvenDigitSumNodes(head)
  
    printList(head)
  
# This code is contributed by rutvik_56

C#




// C# program to remove all
// the Even Digit Sum Nodes from a
// circular singly linked list
using System;
class GFG{
  
// Structure for a node
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)
{
  // Create a new node and make head
  // as next of it.
  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)
  {
    // Find the node before head
    // and update next of it.
    while (temp.next != head_ref)
      temp = temp.next;
 
    temp.next = ptr1;
  }
  else
 
    // Point for the first node
    ptr1.next = ptr1;
 
  head_ref = ptr1;
  return head_ref;
}
  
// Function to delete the node from a
// Circular Linked list
static void 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 the address of the node
  temp.next = del.next;
 
  // Finally, free the memory
  // occupied by del
  del = null;
 
  return;
}
  
// Function to find the digit sum
// for a number
static int digitSum(int num)
{
  int sum = 0;
 
  while (num > 0)
  {
    sum += (num % 10);
    num /= 10;
  }
  return sum;
}
  
// Function to delete all the Even Digit
// Sum Nodes from the singly circular
// linked list
static void deleteEvenDigitSumNodes(Node head)
{
  Node ptr = head;
  Node next;
 
  // Traverse the list till the end
  do
  {
    // If the node's data is Fibonacci,
    // delete node 'ptr'
    if (!(digitSum(ptr.data) % 2 == 1))
      deleteNode(head, ptr);
 
    // Point to the next node
    next = ptr.next;
    ptr = next;
  } while (ptr != head);
}
  
// Function to print nodes in a
// given Circular 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(String[] args)
{
  // Initialize lists as empty
  Node head = null;
 
  // Created linked list will be
  // 9.11.34.6.13.21
  head = push(head, 21);
  head = push(head, 13);
  head = push(head, 6);
  head = push(head, 34);
  head = push(head, 11);
  head = push(head, 9);
 
  deleteEvenDigitSumNodes(head);
  printList(head);
}
}
  
// This code is contributed by 29AjayKumar

Javascript




<script>
// javascript program to remove all
// the Even Digit Sum Nodes 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) {
 
        // Create a new node and make head
        // as next of it.
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) {
 
            // Find the node before head
            // and update next of it.
            while (temp.next != head_ref)
                temp = temp.next;
 
            temp.next = ptr1;
        } else
 
            // Povar for the first node
            ptr1.next = ptr1;
 
        head_ref = ptr1;
        return head_ref;
    }
 
    // Function to delete the node from a
    // Circular Linked list
    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 the address of the node
        temp.next = del.next;
 
        // Finally, free the memory
        // occupied by del
        del = null;
 
        return;
    }
 
    // Function to find the digit sum
    // for a number
    function digitSum(num) {
        var sum = 0;
 
        while (num > 0) {
            sum += (num % 10);
            num = parseInt(num/10);
        }
        return sum;
    }
 
    // Function to delete all the Even Digit
    // Sum Nodes from the singly circular
    // linked list
    function deleteEvenDigitSumNodes(head) {
var ptr = head;
var next;
 
        // Traverse the list till the end
        do {
 
            // If the node's data is Fibonacci,
            // delete node 'ptr'
            if (!(digitSum(ptr.data) % 2 == 1))
                deleteNode(head, ptr);
 
            // Povar to the next node
            next = ptr.next;
            ptr = next;
        } while (ptr != head);
    }
 
    // Function to prvar nodes in a
    // given Circular 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
        // 9.11.34.6.13.21
        head = push(head, 21);
        head = push(head, 13);
        head = push(head, 6);
        head = push(head, 34);
        head = push(head, 11);
        head = push(head, 9);
 
        deleteEvenDigitSumNodes(head);
 
        printList(head);
 
// This code contributed by aashish1995
</script>
Output: 
9 34 21

Time Complexity: O(KN), where N is the size of the linked list and K is the number of digits in the maximum number of the linked list.

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with industry experts, please refer DSA Live Classes




My Personal Notes arrow_drop_up
Recommended Articles
Page :