Traversal of Singly Linked List

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Traversal of Singly Linked List is one of the fundamental operations, where we traverse or visit each node of the linked list. In this article, we will cover how to traverse all the nodes of a singly linked list along with its implementation.

Examples:

Input: 1->2->3->4->5->null
Output: 1 2 3 4 5
Explanation: Every element of each node from head node to last node is printed which means we have traversed each node successfully.

Input: 10->20->30->40->50->null
Output: 10 20 30 40 50
Explanation: Every element of each node from head node to last node is printed which means we have traversed each node successfully.

Input: 5->10->15->20->25->null
Output: 5 10 15 20 25
Explanation: Each node's value is printed sequentially from the head to the last node, confirming successful traversal.

Traversal of Singly Linked List (Iterative Approach)

The process of traversing a singly linked list involves printing the value of each node and then going on to the next node and print that node's value also and so on, till we reach the last node in the singly linked list, whose next node points towards the null.

Step-by-Step Algorithm:

• We will initialize a temporary pointer to the head node of the singly linked list.
• After that, we will check if that pointer is null or not null, if it is null, then return.
• While the pointer is not null, we will access and print the data of the current node, then we move the pointer to next node.

#include <iostream>

using namespace std;

// A linked list node
class Node {
public:
    int data;
    Node* next;

    // Constructor to initialize a new node with data
    Node(int new_data) {
        this->data = new_data;
        this->next = nullptr;
    }
};

// Function to traverse and print the singly linked list
void traverseList(Node* head) {

    // A loop that runs till head is nullptr
    while (head != nullptr) {

        // Printing data of current node
        cout << head->data << " ";

        // Moving to the next node
        head = head->next;
    }
    cout << endl;
}

// Driver Code
int main() {
  
    // Create a hard-coded linked list:
    // 10 -> 20 -> 30 -> 40
    Node* head = new Node(10);
    head->next = new Node(20);
    head->next->next = new Node(30);
    head->next->next->next = new Node(40);

    // Example of traversing the node and printing
    traverseList(head);

    return 0;
}

#include <stdio.h>
#include <stdlib.h>

// A linked list node
struct Node {
    int data;
    struct Node* next;
};

// Function to create a new node
struct Node* createNode(int new_data) {
    struct Node* new_node = 
       (struct Node*)malloc(sizeof(struct Node));
    new_node->data = new_data;
    new_node->next = NULL;
    return new_node;
}

// Function to traverse and print the singly linked list
void traverseList(struct Node* head) {
  
    // Loop that runs until head is NULL
    while (head != NULL) {
      
        // Printing data of current node
        printf("%d ", head->data);

        // Moving to the next node
        head = head->next;
    }
    printf("\n");
}

// Driver code
int main() {
  
    // Create a hard-coded linked list:
    // 10 -> 20 -> 30 -> 40
    struct Node* head = createNode(10);
    head->next = createNode(20);
    head->next->next = createNode(30);
    head->next->next->next = createNode(40);

    // Example of traversing the node and printing
    traverseList(head);

    return 0;
}

// A linked list node
class Node {
    int data;
    Node next;

    // Constructor to initialize a new node with data
    Node(int new_data) {
        this.data = new_data;
        this.next = null;
    }
}

public class GfG {

    // Function to traverse and print the singly linked list
    public static void traverseList(Node head) {

        // A loop that runs till head is nullptr
        while (head != null) {

            // Printing data of current node
            System.out.print(head.data + " ");

            // Moving to the next node
            head = head.next;
        }
        System.out.println();
    }

    // Driver code
    public static void main(String[] args) {
      
        // Create a hard-coded linked list:
        // 10 -> 20 -> 30 -> 40
        Node head = new Node(10);
        head.next = new Node(20);
        head.next.next = new Node(30);
        head.next.next.next = new Node(40);

        // Example of traversing the node and printing
        traverseList(head);
    }
}

# A linked list node
class Node:

    # Constructor to initialize a new node with data
    def __init__(self, new_data):
        self.data = new_data
        self.next = None

# Function to traverse and print the singly linked list
def traverseList(head):

    # A loop that runs till head is nullptr
    while head is not None:

		# Printing data of current node
        print(head.data, end=" ")
        
		# Moving to the next node
        head = head.next
    print()

# Driver code
def main():

    # Create a hard-coded linked list:
    # 10 -> 20 -> 30 -> 40
    head = Node(10)
    head.next = Node(20)
    head.next.next = Node(30)
    head.next.next.next = Node(40)

    # Example of traversing the node and printing
    traverseList(head)


if __name__ == "__main__":
    main()

using System;

// A linked list node
class Node {
    public int Data { get;set; }
    public Node Next { get;set; }

    // Constructor to initialize a new node with data
    public Node(int new_data) {
        Data = new_data;
        Next = null;
    }
}

class GfG {

    // Function to traverse and print the singly linked list
    static void TraverseList(Node head) {

        // A loop that runs till head is nullptr
        while (head != null) {

            // Printing data of current node
            Console.Write(head.Data + " ");

            // Moving to the next node
            head = head.Next;
        }
        Console.WriteLine();
    }

    // Driver Code
    public static void Main(string[] args) {
      
        // Create a hard-coded linked list:
        // 10 -> 20 -> 30 -> 40
        Node head = new Node(10);
        head.Next = new Node(20);
        head.Next.Next = new Node(30);
        head.Next.Next.Next = new Node(40);

        // Example of traversing the node and printing
        TraverseList(head);
    }
}

// A linked list node
class Node {

    // Constructor to initialize a new node with data
    constructor(new_data)
    {
        this.data = new_data;
        this.next = null;
    }
}

// Function to traverse and print the singly linked list
function traverseList(head)
{

    // A loop that runs till head is nullptr
    while (head != null) {

        // Printing data of current node
        process.stdout.write(head.data + " ");

        // Moving to the next node
        head = head.next;
    }
    console.log();
}

// Driver code
function main()
{

    // Create a hard-coded linked list:
    // 10 -> 20 -> 30 -> 40
    let head = new Node(10);
    head.next = new Node(20);
    head.next.next = new Node(30);
    head.next.next.next = new Node(40);

    // Example of traversing the node and printing
    traverseList(head);
}

// Calling the main method to execute the code
main();

10 20 30 40 

Time Complexity: O(n), where n is the number of nodes in the linked list.
Auxiliary Space: O(1)

Traversal of Singly Linked List (Recursive Approach)

We can also traverse the singly linked list using recursion. We start at the head node of the singly linked list, check if it is null or not and print its value. We then call the traversal function again with the next node passed as pointer.

Step-by-Step Algorithm:

• Firstly, we define a recursive method to traverse the singly linked list, which takes a node as a parameter.
• In this function, the base case is that if the node is null then we will return from the recursive method.
• We then pass the head node as the parameter to this function.
• After that, we access and print the data of the current node.
• At last, we will make a recursive call to this function with the next node as the parameter.

#include <iostream>

using namespace std;

// A linked list node
class Node {
public:
    int data;
    Node* next;

    // Constructor to initialize a new node with data
    Node(int new_data) {
        this->data = new_data;
        this->next = nullptr;
    }
};

// Function to traverse and print the singly linked list
void traverseList(Node* head) {

    // Base condition is when the head is nullptr
    if (head == nullptr) {
        cout << endl;
        return;
    }

    // Printing the current node data
    cout << head->data << " ";

    // Moving to the next node
    traverseList(head->next);
}

// Driver code
int main() {
  
    // Create a hard-coded linked list:
    // 10 -> 20 -> 30 -> 40
    Node* head = new Node(10);
    head->next = new Node(20);
    head->next->next = new Node(30);
    head->next->next->next = new Node(40);

    // Example of traversing the node and printing
    traverseList(head);

    return 0;
}

#include <stdio.h>
#include <stdlib.h>

// A linked list node
struct Node {
    int data;
    struct Node* next;
};

// Function to create a new node with given data
struct Node* createNode(int new_data) {
    struct Node* new_node
        = (struct Node*)malloc(sizeof(struct Node));
    new_node->data = new_data;
    new_node->next = NULL;
    return new_node;
}

// Function to traverse and print the singly linked list
void traverseList(struct Node* head) {
  
    // Base condition is when the head is nullptr
    if (head == NULL) {
        printf("\n");
        return;
    }

    // Printing the current node data
    printf("%d ", head->data);

    // Moving to the next node
    traverseList(head->next);
}

// Driver code
int main() {
  
    // Create a hard-coded linked list:
    // 10 -> 20 -> 30 -> 40
    struct Node* head = createNode(10);
    head->next = createNode(20);
    head->next->next = createNode(30);
    head->next->next->next = createNode(40);

    // Example of traversing the node and printing
    traverseList(head);

    return 0;
}

// A linked list node
class Node {
    int data;
    Node next;

    // Constructor to initialize a new node with data
    Node(int new_data) {
        data = new_data;
        next = null;
    }
}

public class GfG {

    // Function to traverse and print the singly linked list
    static void traverseList(Node head) {

        // Base condition is when the head is nullptr
        if (head == null) {
            System.out.println();
            return;
        }

        // Printing the current node data
        System.out.print(head.data + " ");

        // Moving to the next node
        traverseList(head.next);
    }

    // driver code
    public static void main(String[] args) {
      
        // Create a hard-coded linked list:
        // 10 -> 20 -> 30 -> 40
        Node head = new Node(10);
        head.next = new Node(20);
        head.next.next = new Node(30);
        head.next.next.next = new Node(40);

        // Example of traversing the node and printing
        traverseList(head);
    }
}

# A linked list node
class Node:
    def __init__(self, data):
      
        # Constructor to initialize a new node with data
        self.data = data
        self.next = None

# Function to traverse and print the singly linked list
def traverseList(head):
  
    # Base condition is when the head is nullptr
    if head is None:
        print()
        return
      
    # Printing the current node data
    print(head.data, end=" ")
    
    # Moving to the next node
    traverseList(head.next)

# Driver code
def main():
  
    # Create a hard-coded linked list:
    # 10 -> 20 -> 30 -> 40
    head = Node(10)
    head.next = Node(20)
    head.next.next = Node(30)
    head.next.next.next = Node(40)

    # Example of traversing the node and printing
    traverseList(head)

if __name__ == "__main__":
    main()

using System;

// A linked list node
class Node {
    public int Data { get;set; }
    public Node Next { get;set; }

    // Constructor to initialize a new node with data
    public Node(int newData) {
        Data = newData;
        Next = null;
    }
}

class GfG {

    // Function to traverse and print the singly linked list
    static void TraverseList(Node head) {
      
        // Base condition is when the head is nullptr
        if (head == null) {
            Console.WriteLine();
            return;
        }

        // Printing the current node data
        Console.Write(head.Data + " ");

        // Moving to the next node
        TraverseList(head.Next);
    }

    // Driver code
    static void Main() {
      
        // Create a hard-coded linked list:
        // 10 -> 20 -> 30 -> 40
        Node head = new Node(10);
        head.Next = new Node(20);
        head.Next.Next = new Node(30);
        head.Next.Next.Next = new Node(40);

        // Example of traversing the node and printing
        TraverseList(head);
    }
}

// A linked list node
class Node {

    // Constructor to initialize a new node with data
    constructor(new_data) {
        this.data = new_data;
        this.next = null;
    }
}

// Function to traverse and print the singly linked list
function traverseList(head) {

    // Base condition is when the head is nullptr
    if (head === null) {
        console.log();
        return;
    }

    // Printing the current node data
    process.stdout.write(head.data + " ");

    // Moving to the next node
    traverseList(head.next);
}

// Driver code
function main() {

    // Create a hard-coded linked list:
    // 10 -> 20 -> 30 -> 40
    let head = new Node(10);
    head.next = new Node(20);
    head.next.next = new Node(30);
    head.next.next.next = new Node(40);

    // Example of traversing the node and printing
    traverseList(head);
}

main();

10 20 30 40 

Time Complexity: O(n), where n is number of nodes in the linked list.
Auxiliary Space: O(n) because of recursive stack space.