Recursive insertion and traversal linked list
We have discussed different methods of linked list insertion. How to recursively create a linked list?
Recursively inserting at the end: To create a Linked list using recursion follow these steps. Below steps insert a new node recursively at the end of linked list.
C++
// Function to insert a new node at the // end of linked list using recursion. Node* insertEnd(Node* head, int data) { // If linked list is empty, create a // new node (Assuming newNode() allocates // a new node with given data) if (head == NULL) return newNode(data); // If we have not reached end, keep traversing // recursively. else head->next = insertEnd(head->next, data); return head; } |
Java
// Function to insert a new node at the // end of linked list using recursion. static Node insertEnd(Node head, int data) { // If linked list is empty, create a // new node (Assuming newNode() allocates // a new node with given data) if (head == null ) return newNode(data); // If we have not reached end, keep traversing // recursively. else head.next = insertEnd(head.next, data); return head; } // This code is contributed by rutvik_56 |
Python3
# Function to insert a new node at the # end of linked list using recursion. def insertEnd(head, data): # If linked list is empty, create a # new node (Assuming newNode() allocates # a new node with given data) if (head = = None ): return newNode(data) # If we have not reached end, # keep traversing recursively. else : head. next = insertEnd(head. next , data) return head # This code is contributed by divyeshrabadiya07 |
C#
// Function to insert a new node at the // end of linked list using recursion. static Node insertEnd(Node head, int data) { // If linked list is empty, create a // new node (Assuming newNode() allocates // a new node with given data) if (head == null ) return newNode(data); // If we have not reached end, keep traversing // recursively. else head.next = insertEnd(head.next, data); return head; } // This code is contributed by divyesh072019 |
Javascript
<script> // Function to insert a new node at the // end of linked list using recursion. function insertEnd(head , data) { // If linked list is empty, create a // new node (Assuming newNode() allocates // a new node with given data) if (head == null ) { return newNode(data); } // If we have not reached end, keep traversing // recursively. else { head.next = insertEnd(head.next, data); } return head; } // This code is contributed by shubhamsingh10 </script> |
Recursively traversing the list:
The idea is simple, we print current node and recur for remaining list.
C++
void traverse(Node* head) { if (head == NULL) return ; // If head is not NULL, print current node // and recur for remaining list cout << head->data << " " ; traverse(head->next); } |
Java
static void traverse(Node head) { if (head == null ) return ; // If head is not null, print current node // and recur for remaining list System.out.print( head.data + " " ); traverse(head.next); } // This code is contributed by SUBHAMSINGH10 |
Python3
def traverse(head): if (head = = None ): return # If head is not None, print current node # and recur for remaining list print (head.data, end = " " ); traverse(head. next ) # This code is contributed by Pratham76 |
C#
static void traverse(Node head) { if (head == null ) return ; // If head is not null, print current node // and recur for remaining list Console.Write(head.data + " " ); traverse(head.next); } |
Javascript
function traverse(head){ if (head == null ) return ; // If head is not NULL, print current node // and recur for remaining list console.log(head.data + " " ); traverse(head.next); } // This code is contributed by Yash Agarwal(yashagarwal2852002) |
Complete Program: Below is complete program to demonstrate working of insert and traverse a linked list.
C++
// Recursive C++ program to recursively insert // a node and recursively print the list. #include <bits/stdc++.h> using namespace std; struct Node { int data; Node* next; }; // Allocates a new node with given data Node *newNode( int data) { Node *new_node = new Node; new_node->data = data; new_node->next = NULL; return new_node; } // Function to insert a new node at the // end of linked list using recursion. Node* insertEnd(Node* head, int data) { // If linked list is empty, create a // new node (Assuming newNode() allocates // a new node with given data) if (head == NULL) return newNode(data); // If we have not reached end, keep traversing // recursively. else head->next = insertEnd(head->next, data); return head; } void traverse(Node* head) { if (head == NULL) return ; // If head is not NULL, print current node // and recur for remaining list cout << head->data << " " ; traverse(head->next); } // Driver code int main() { Node* head = NULL; head = insertEnd(head, 6); head = insertEnd(head, 8); head = insertEnd(head, 10); head = insertEnd(head, 12); head = insertEnd(head, 14); traverse(head); } |
Java
// Recursive Java program to recursively insert // a node and recursively print the list. class GFG { static class Node { int data; Node next; }; // Allocates a new node with given data static Node newNode( int data) { Node new_node = new Node(); new_node.data = data; new_node.next = null ; return new_node; } // Function to insert a new node at the // end of linked list using recursion. static Node insertEnd(Node head, int data) { // If linked list is empty, create a // new node (Assuming newNode() allocates // a new node with given data) if (head == null ) return newNode(data); // If we have not reached end, keep traversing // recursively. else head.next = insertEnd(head.next, data); return head; } static void traverse(Node head) { if (head == null ) return ; // If head is not null, print current node // and recur for remaining list System.out.print( head.data + " " ); traverse(head.next); } // Driver code public static void main(String args[]) { Node head = null ; head = insertEnd(head, 6 ); head = insertEnd(head, 8 ); head = insertEnd(head, 10 ); head = insertEnd(head, 12 ); head = insertEnd(head, 14 ); traverse(head); } } // This code is contributed by andrew1234 |
Python3
# Recursive Python3 program to # recursively insert a node and # recursively print the list. import math class Node: def __init__( self , data): self .data = data self . next = None # Allocates a new node with given data def newNode(data): new_node = Node(data) new_node.data = data new_node. next = None return new_node # Function to insert a new node at the # end of linked list using recursion. def insertEnd(head, data): # If linked list is empty, create a # new node (Assuming newNode() allocates # a new node with given data) if (head = = None ): return newNode(data) # If we have not reached end, # keep traversing recursively. else : head. next = insertEnd(head. next , data) return head def traverse(head): if (head = = None ): return # If head is not None, print current node # and recur for remaining list print (head.data, end = " " ); traverse(head. next ) # Driver code if __name__ = = '__main__' : head = None head = insertEnd(head, 6 ) head = insertEnd(head, 8 ) head = insertEnd(head, 10 ) head = insertEnd(head, 12 ) head = insertEnd(head, 14 ) traverse(head) # This code is contributed by sapna singh |
C#
// Recursive C# program to recursively insert // a node and recursively print the list. using System; class GFG { public class Node { public int data; public Node next; }; // Allocates a new node with given data static Node newNode( int data) { Node new_node = new Node(); new_node.data = data; new_node.next = null ; return new_node; } // Function to insert a new node at the // end of linked list using recursion. static Node insertEnd(Node head, int data) { // If linked list is empty, create a // new node (Assuming newNode() allocates // a new node with given data) if (head == null ) return newNode(data); // If we have not reached end, keep traversing // recursively. else head.next = insertEnd(head.next, data); return head; } static void traverse(Node head) { if (head == null ) return ; // If head is not null, print current node // and recur for remaining list Console.Write(head.data + " " ); traverse(head.next); } // Driver code public static void Main(String []args) { Node head = null ; head = insertEnd(head, 6); head = insertEnd(head, 8); head = insertEnd(head, 10); head = insertEnd(head, 12); head = insertEnd(head, 14); traverse(head); } } // This code is contributed by 29AjayKumar |
Javascript
<script> // Recursive Javascript program to recursively insert // a node and recursively print the list. class Node { constructor(data) { this .next = null ; this .data = data; } } // Allocates a new node with given data function newNode(data) { let new_node = new Node(data); return new_node; } // Function to insert a new node at the // end of linked list using recursion. function insertEnd(head, data) { // If linked list is empty, create a // new node (Assuming newNode() allocates // a new node with given data) if (head == null ) return newNode(data); // If we have not reached end, keep traversing // recursively. else head.next = insertEnd(head.next, data); return head; } function traverse(head) { if (head == null ) return ; // If head is not null, print current node // and recur for remaining list document.write(head.data + " " ); traverse(head.next); } let head = null ; head = insertEnd(head, 6); head = insertEnd(head, 8); head = insertEnd(head, 10); head = insertEnd(head, 12); head = insertEnd(head, 14); traverse(head); // This code is contributed by mukesh07. </script> |
6 8 10 12 14
Time Complexity: O(N), to traverse the linked list of size N.
Auxiliary Space: O(N), for recursion call stack
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