Find Length of a Linked List (Iterative and Recursive)
Last Updated :
18 Feb, 2025
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Given a Singly Linked List, the task is to find the Length of the Linked List.
Examples:
Input: LinkedList = 1->3->1->2->1
Output: 5
Explanation: The linked list has 5 nodes.Input: LinkedList = 2->4->1->9->5->3->6
Output: 7
Explanation: The linked list has 7 nodes.Input:
LinkedList = 10->20->30->40->50->60
Output:6
Explanation: The linked list has 6 nodes.
Iterative Approach to Find the Length of a Linked List
The idea is similar to traversal of Linked List with an additional variable to count the number of nodes in the Linked List.
Steps to find the length of the Linked List:
- Initialize count as 0.
- Initialize a node pointer, curr = head.
- Do following while curr is not NULL
- curr = curr -> next
- Increment count by 1.
- Return count.
// Iterative C++ program to find length
// or count of nodes in a linked list
#include <bits/stdc++.h>
using namespace std;
// Link list node
class Node {
public:
int data;
Node* next;
// Constructor to initialize a new node with data
Node(int new_data) {
data = new_data;
next = nullptr;
}
};
// Counts number of nodes in linked list
int countNodes(Node* head) {
// Initialize count with 0
int count = 0;
// Initialize curr with head of Linked List
Node* curr = head;
// Traverse till we reach nullptr
while (curr != nullptr) {
// Increment count by 1
count++;
// Move pointer to next node
curr = curr->next;
}
// Return the count of nodes
return count;
}
// Driver code
int main() {
// Create a hard-coded linked list:
// 1 -> 3 -> 1 -> 2 -> 1
Node* head = new Node(1);
head->next = new Node(3);
head->next->next = new Node(1);
head->next->next->next = new Node(2);
head->next->next->next->next = new Node(1);
// Function call to count the number of nodes
cout << "Count of nodes is " << countNodes(head);
return 0;
}
// Iterative C program to find length or count of nodes in a
// linked list
#include <stdio.h>
#include <stdlib.h>
// Link 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;
}
// Counts number of nodes in linked list
int countNodes(struct Node* head) {
// Initialize count with 0
int count = 0;
// Initialize curr with head of Linked List
struct Node* curr = head;
// Traverse till we reach NULL
while (curr != NULL) {
// Increment count by 1
count++;
// Move pointer to next node
curr = curr->next;
}
// Return the count of nodes
return count;
}
// Driver code
int main() {
// Create a hard-coded linked list:
// 1 -> 3 -> 1 -> 2 -> 1
struct Node* head = createNode(1);
head->next = createNode(3);
head->next->next = createNode(1);
head->next->next->next = createNode(2);
head->next->next->next->next = createNode(1);
// Function call
printf("Count of nodes is %d", countNodes(head));
return 0;
}
// Iterative Java program to count the number of
// nodes in a linked list
// Node class to define a linked list node
class Node {
int data;
Node next;
// Constructor to initialize a new node with data
Node(int newData) {
data = newData;
next = null;
}
}
// Class to define methods related to the linked list
public class GFG {
// Counts number of nodes in linked list
public static int countNodes(Node head) {
// Initialize count with 0
int count = 0;
// Initialize curr with head of Linked List
Node curr = head;
// Traverse till we reach null
while (curr != null) {
// Increment count by 1
count++;
// Move pointer to next node
curr = curr.next;
}
// Return the count of nodes
return count;
}
// Driver code
public static void main(String[] args) {
// Create a hard-coded linked list:
// 1 -> 3 -> 1 -> 2 -> 1
Node head = new Node(1);
head.next = new Node(3);
head.next.next = new Node(1);
head.next.next.next = new Node(2);
head.next.next.next.next = new Node(1);
// Function call to count the number of nodes
System.out.println("Count of nodes is "
+ countNodes(head));
}
}
# Iterative Python program to count the number of nodes
# in a linked list
class Node:
def __init__(self, new_data):
# Constructor to initialize a new node with data
self.data = new_data
self.next = None
def count_nodes(head):
# Counts number of nodes in linked list
# Initialize count with 0
count = 0
# Initialize curr with head of Linked List
curr = head
# Traverse till we reach None
while curr is not None:
# Increment count by 1
count += 1
# Move pointer to next node
curr = curr.next
# Return the count of nodes
return count
# Driver code
if __name__ == "__main__":
# Create a hard-coded linked list:
# 1 -> 3 -> 1 -> 2 -> 1
head = Node(1)
head.next = Node(3)
head.next.next = Node(1)
head.next.next.next = Node(2)
head.next.next.next.next = Node(1)
# Function call to count the number of nodes
print("Count of nodes is", count_nodes(head))
// Iterative C# program to find length or count of nodes
// in a linked list
using System;
// Link list node
class Node {
public int Data;
public Node Next;
// Constructor to initialize a new node with data
public Node(int newData) {
Data = newData;
Next = null;
}
}
class GFG {
// Counts number of nodes in linked list
static int CountNodes(Node head) {
// Initialize count with 0
int count = 0;
// Initialize curr with head of Linked List
Node curr = head;
// Traverse till we reach null
while (curr != null) {
// Increment count by 1
count++;
// Move pointer to next node
curr = curr.Next;
}
// Return the count of nodes
return count;
}
static void Main() {
// Create a hard-coded linked list:
// 1 -> 3 -> 1 -> 2 -> 1
Node head = new Node(1);
head.Next = new Node(3);
head.Next.Next = new Node(1);
head.Next.Next.Next = new Node(2);
head.Next.Next.Next.Next = new Node(1);
// Function call to count the number of nodes
Console.WriteLine("Count of nodes is "
+ CountNodes(head));
}
}
// Iterative JavaScript program to find length
// or count of nodes in a linked list
// Linked List Node
class Node {
// Constructor to initialize a new node
// with data
constructor(newData) {
this.data = newData;
this.next = null;
}
}
// Counts number of nodes in linked list
function countNodes(head) {
// Initialize count with 0
let count = 0;
// Initialize curr with head of Linked List
let curr = head;
// Traverse till we reach null
while (curr !== null) {
// Increment count by 1
count++;
// Move pointer to next node
curr = curr.next;
}
// Return the count of nodes
return count;
}
// Driver code
// Create a hard-coded linked list:
// 1 -> 3 -> 1 -> 2 -> 1
let head = new Node(1);
head.next = new Node(3);
head.next.next = new Node(1);
head.next.next.next = new Node(2);
head.next.next.next.next = new Node(1);
// Function call to count the number of nodes
console.log("Count of nodes is " + countNodes(head));
Output
Count of nodes is 5
Time complexity: O(n), Where n is the size of the linked list
Auxiliary Space: O(1), As constant extra space is used.
Recursive Approach to Find the Length of a Linked List:
The idea is to use recursion by maintaining a function, say countNodes(node) which takes a node as an argument and calls itself with the next node until we reach the end of the Linked List. Each of the recursive call returns 1 + count of remaining nodes.
// Recursive C++ program to find length
// or count of nodes in a linked list
#include <bits/stdc++.h>
using namespace std;
// Link list node
class Node {
public:
int data;
Node* next;
// Constructor to initialize a new node with data
Node(int new_data) {
data = new_data;
next = nullptr;
}
};
// Recursively count number of nodes in linked list
int countNodes(Node* head) {
// Base Case
if (head == NULL) {
return 0;
}
// Count this node plus the rest of the list
return 1 + countNodes(head->next);
}
// Driver code
int main() {
// Create a hard-coded linked list:
// 1 -> 3 -> 1 -> 2 -> 1
Node* head = new Node(1);
head->next = new Node(3);
head->next->next = new Node(1);
head->next->next->next = new Node(2);
head->next->next->next->next = new Node(1);
// Function call to count the number of nodes
cout << "Count of nodes is " << countNodes(head);
return 0;
}
// Recursive C program to find length
// or count of nodes in a linked list
#include <stdio.h>
#include <stdlib.h>
// Link list node
struct Node {
int data;
struct Node* next;
};
// Constructor to initialize a new node with 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;
}
// Recursively count number of nodes in linked list
int countNodes(struct Node* head) {
// Base Case
if (head == NULL) {
return 0;
}
// Count this node plus the rest of the list
return 1 + countNodes(head->next);
}
// Driver code
int main() {
// Create a hard-coded linked list:
// 1 -> 3 -> 1 -> 2 -> 1
struct Node* head = createNode(1);
head->next = createNode(3);
head->next->next = createNode(1);
head->next->next->next = createNode(2);
head->next->next->next->next = createNode(1);
// Function call to count the number of nodes
printf("Count of nodes is %d\n", countNodes(head));
return 0;
}
// Recursive Java program to find length
// or count of nodes in a linked list
// Link 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;
}
}
// Recursively count number of nodes in linked list
public class GFG {
public static int countNodes(Node head) {
// Base Case
if (head == null) {
return 0;
}
// Count this node plus the rest of the list
return 1 + countNodes(head.next);
}
public static void main(String[] args) {
// Create a hard-coded linked list:
// 1 -> 3 -> 1 -> 2 -> 1
Node head = new Node(1);
head.next = new Node(3);
head.next.next = new Node(1);
head.next.next.next = new Node(2);
head.next.next.next.next = new Node(1);
// Function call to count the number of nodes
System.out.println("Count of nodes is "
+ countNodes(head));
}
}
# Recursive Python program to find length
# or count of nodes in a linked list
# Linked List Node
class Node:
def __init__(self, new_data):
self.data = new_data
self.next = None
# Recursively count number of nodes in linked list
def count_nodes(head):
# Base Case
if head is None:
return 0
# Count this node plus the rest of the list
return 1 + count_nodes(head.next)
# Driver code
if __name__ == "__main__":
# Create a hard-coded linked list:
# 1 -> 3 -> 1 -> 2 -> 1
head = Node(1)
head.next = Node(3)
head.next.next = Node(1)
head.next.next.next = Node(2)
head.next.next.next.next = Node(1)
# Function call to count the number of nodes
print("Count of nodes is", count_nodes(head))
// Recursive C# program to find length
// or count of nodes in a linked list
using System;
// Link list node
public class Node {
public int Data;
public Node Next;
// Constructor to initialize a new node with data
public Node(int new_data) {
Data = new_data;
Next = null;
}
}
// Recursively count number of nodes in linked list
public class GFG {
public static int CountNodes(Node head) {
// Base Case
if (head == null) {
return 0;
}
// Count this node plus the rest of the list
return 1 + CountNodes(head.Next);
}
// Driver code
public static void Main() {
// Create a hard-coded linked list:
// 1 -> 3 -> 1 -> 2 -> 1
Node head = new Node(1);
head.Next = new Node(3);
head.Next.Next = new Node(1);
head.Next.Next.Next = new Node(2);
head.Next.Next.Next.Next = new Node(1);
// Function call to count the number of nodes
Console.WriteLine("Count of nodes is " + CountNodes(head));
}
}
// Recursive Javascript program to find length
// or count of nodes in a linked list
// Link list node
class Node {
constructor(data) {
this.data = data;
this.next = null;
}
}
// Recursively count number of nodes in linked list
function countNodes(head) {
// Base Case
if (head === null) {
return 0;
}
// Count this node plus the rest of the list
return 1 + countNodes(head.next);
}
// Driver code
// Create a hard-coded linked list:
// 1 -> 3 -> 1 -> 2 -> 1
let head = new Node(1);
head.next = new Node(3);
head.next.next = new Node(1);
head.next.next.next = new Node(2);
head.next.next.next.next = new Node(1);
// Function call to count the number of nodes
console.log("Count of nodes is " + countNodes(head));
Output
Count of nodes is 5
Time Complexity: O(n), where n is the length of Linked List.
Auxiliary Space: O(n), Extra space is used in the recursion call stack.
