Circular Singly Linked List - Insert a new node at the start
In this method, a new node is inserted at the start of the circular singly linked list. For example - if the given List is 10->20->30 and a new element 100 is added at the start, the List becomes 100->10->20->30.
Inserting a new node at the start of the circular singly linked list is very easy. First, a new node with given element is created. It is then added at the start of the list by linking the head node and last node to the new node.
The function push_front is created for this purpose. It is a 6-step process.
void push_front(int newElement) { //1. allocate node Node* newNode = new Node(); //2. assign data element newNode->data = newElement; //3. assign null to the next of new node newNode->next = NULL; //4. Check the list is empty or not, // if empty make the new node as head if(head == NULL) { head = newNode; newNode->next = head; } else { //5. Else, traverse to the last node Node* temp = head; while(temp->next != head) temp = temp->next; //6. Adjust the links temp->next = newNode; newNode->next = head; head = newNode; } }
void push_front(struct Node** head_ref, int newElement) { //1. allocate node struct Node *newNode, *temp; newNode = (struct Node*)malloc(sizeof(struct Node)); //2. assign data element newNode->data = newElement; //3. assign null to the next of new node newNode->next = NULL; //4. Check the list is empty or not, // if empty make the new node as head if(*head_ref == NULL) { *head_ref = newNode; newNode->next = *head_ref; } else { //5. Else, traverse to the last node temp = *head_ref; while(temp->next != *head_ref) { temp = temp->next; } //6. Adjust the links temp->next = newNode; newNode->next = *head_ref; *head_ref = newNode; } }
def push_front(self, newElement): #1 & 2 & 3. allocate node, assign data element # assign null to the next of new node newNode = Node(newElement) #4. Check the list is empty or not, # if empty make the new node as head if(self.head == None): self.head = newNode newNode.next = self.head return else: #5. Else, traverse to the last node temp = self.head while(temp.next != self.head): temp = temp.next #6. Adjust the links temp.next = newNode newNode.next = self.head self.head = newNode
void push_front(int newElement) { //1. allocate node Node newNode = new Node(); //2. assign data element newNode.data = newElement; //3. assign null to the next of new node newNode.next = null; //4. Check the list is empty or not, // if empty make the new node as head if(head == null) { head = newNode; newNode.next = head; } else { //5. Else, traverse to the last node Node temp = new Node(); temp = head; while(temp.next != head) temp = temp.next; //6. Adjust the links temp.next = newNode; newNode.next = head; head = newNode; } }
public void push_front(int newElement) { //1. allocate node Node newNode = new Node(); //2. assign data element newNode.data = newElement; //3. assign null to the next of new node newNode.next = null; //4. Check the list is empty or not, // if empty make the new node as head if(head == null) { head = newNode; newNode.next = head; } else { //5. Else, traverse to the last node Node temp = new Node(); temp = head; while(temp.next != head) temp = temp.next; //6. Adjust the links temp.next = newNode; newNode.next = head; head = newNode; } }
public function push_front($newElement) { //1. allocate node $newNode = new Node(); //2. assign data element $newNode->data = $newElement; //3. assign null to the next of new node $newNode->next = null; //4. Check the list is empty or not, // if empty make the new node as head if($this->head == null) { $this->head = $newNode; $newNode->next = $this->head; } else { //5. Else, traverse to the last node $temp = new Node(); $temp = $this->head; while($temp->next !== $this->head) { $temp = $temp->next; } //6. Adjust the links $temp->next = $newNode; $newNode->next = $this->head; $this->head = $newNode; } }
The below is a complete program that uses above discussed concept to insert new node at the start of the circular singly linked list.
#include <iostream> using namespace std; //node structure struct Node { int data; Node* next; }; class LinkedList { private: Node* head; public: LinkedList(){ head = NULL; } //Add new element at the start of the list void push_front(int newElement) { Node* newNode = new Node(); newNode->data = newElement; newNode->next = NULL; if(head == NULL) { head = newNode; newNode->next = head; } else { Node* temp = head; while(temp->next != head) temp = temp->next; temp->next = newNode; newNode->next = head; head = newNode; } } //display the content of the list void PrintList() { Node* temp = head; if(temp != NULL) { cout<<"The list contains: "; while(true) { cout<<temp->data<<" "; temp = temp->next; if(temp == head) break; } cout<<endl; } else { cout<<"The list is empty.\n"; } } }; // test the code int main() { LinkedList MyList; //Add three elements at the start of the list. MyList.push_front(10); MyList.push_front(20); MyList.push_front(30); MyList.PrintList(); return 0; }
The above code will give the following output:
The list contains: 30 20 10
#include <stdio.h> #include <stdlib.h> //node structure struct Node { int data; struct Node* next; }; //Add new element at the start of the list void push_front(struct Node** head_ref, int newElement) { struct Node *newNode, *temp; newNode = (struct Node*)malloc(sizeof(struct Node)); newNode->data = newElement; newNode->next = NULL; if(*head_ref == NULL) { *head_ref = newNode; newNode->next = *head_ref; } else { temp = *head_ref; while(temp->next != *head_ref) { temp = temp->next; } temp->next = newNode; newNode->next = *head_ref; *head_ref = newNode; } } //display the content of the list void PrintList(struct Node* head_ref) { struct Node* temp = head_ref; if(head_ref != NULL) { printf("The list contains: "); while (1) { printf("%i ",temp->data); temp = temp->next; if(temp == head_ref) break; } printf("\n"); } else { printf("The list is empty.\n"); } } // test the code int main() { struct Node* MyList = NULL; //Add three elements at the start of the list. push_front(&MyList, 10); push_front(&MyList, 20); push_front(&MyList, 30); PrintList(MyList); return 0; }
The above code will give the following output:
The list contains: 30 20 10
# node structure class Node: def __init__(self, data): self.data = data self.next = None #class Linked List class LinkedList: def __init__(self): self.head = None #Add new element at the start of the list def push_front(self, newElement): newNode = Node(newElement) if(self.head == None): self.head = newNode newNode.next = self.head return else: temp = self.head while(temp.next != self.head): temp = temp.next temp.next = newNode newNode.next = self.head self.head = newNode #display the content of the list def PrintList(self): temp = self.head if(temp != None): print("The list contains:", end=" ") while (True): print(temp.data, end=" ") temp = temp.next if(temp == self.head): break print() else: print("The list is empty.") # test the code MyList = LinkedList() #Add three elements at the start of the list. MyList.push_front(10) MyList.push_front(20) MyList.push_front(30) MyList.PrintList()
The above code will give the following output:
The list contains: 30 20 10
//node structure class Node { int data; Node next; }; class LinkedList { Node head; LinkedList(){ head = null; } //Add new element at the start of the list void push_front(int newElement) { Node newNode = new Node(); newNode.data = newElement; newNode.next = null; if(head == null) { head = newNode; newNode.next = head; } else { Node temp = new Node(); temp = head; while(temp.next != head) temp = temp.next; temp.next = newNode; newNode.next = head; head = newNode; } } //display the content of the list void PrintList() { Node temp = new Node(); temp = this.head; if(temp != null) { System.out.print("The list contains: "); while(true) { System.out.print(temp.data + " "); temp = temp.next; if(temp == this.head) break; } System.out.println(); } else { System.out.println("The list is empty."); } } }; // test the code public class Implementation { public static void main(String[] args) { LinkedList MyList = new LinkedList(); //Add three elements at the start of the list. MyList.push_front(10); MyList.push_front(20); MyList.push_front(30); MyList.PrintList(); } }
The above code will give the following output:
The list contains: 30 20 10
using System; //node structure class Node { public int data; public Node next; }; class LinkedList { Node head; public LinkedList(){ head = null; } //Add new element at the start of the list public void push_front(int newElement) { Node newNode = new Node(); newNode.data = newElement; newNode.next = null; if(head == null) { head = newNode; newNode.next = head; } else { Node temp = new Node(); temp = head; while(temp.next != head) temp = temp.next; temp.next = newNode; newNode.next = head; head = newNode; } } //display the content of the list public void PrintList() { Node temp = new Node(); temp = this.head; if(temp != null) { Console.Write("The list contains: "); while(true) { Console.Write(temp.data + " "); temp = temp.next; if(temp == this.head) break; } Console.WriteLine(); } else { Console.WriteLine("The list is empty."); } } }; // test the code class Implementation { static void Main(string[] args) { LinkedList MyList = new LinkedList(); //Add three elements at the start of the list. MyList.push_front(10); MyList.push_front(20); MyList.push_front(30); MyList.PrintList(); } }
The above code will give the following output:
The list contains: 30 20 10
<?php //node structure class Node { public $data; public $next; } class LinkedList { public $head; public function __construct(){ $this->head = null; } //Add new element at the start of the list public function push_front($newElement) { $newNode = new Node(); $newNode->data = $newElement; $newNode->next = null; if($this->head == null) { $this->head = $newNode; $newNode->next = $this->head; } else { $temp = new Node(); $temp = $this->head; while($temp->next !== $this->head) { $temp = $temp->next; } $temp->next = $newNode; $newNode->next = $this->head; $this->head = $newNode; } } //display the content of the list public function PrintList() { $temp = new Node(); $temp = $this->head; if($temp != null) { echo "The list contains: "; while(true) { echo $temp->data." "; $temp = $temp->next; if($temp == $this->head) break; } echo "\n"; } else { echo "The list is empty.\n"; } } }; // test the code $MyList = new LinkedList(); //Add three elements at the start of the list. $MyList->push_front(10); $MyList->push_front(20); $MyList->push_front(30); $MyList->PrintList(); ?>
The above code will give the following output:
The list contains: 30 20 10