linkedList.definition

linkedList.descriptionPart1

linkedList.descriptionPart2

linkedList.keyPointsTitle

linkedList.keyPoint1
linkedList.keyPoint2
linkedList.keyPoint3
linkedList.keyPoint4

linkedList.exampleTitle

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linkedList.syntaxTitle

// Java
class Node {
    int value;
    Node next;

    Node(int value) {
        this.value = value;
    }
}

class LinkedListExample {
    Node head;

    // Insert at end
    void insert(int value) {
        Node newNode = new Node(value);
        if (head == null) {
            head = newNode;
            return;
        }
        Node current = head;
        while (current.next != null) {
            current = current.next;
        }
        current.next = newNode;
    }
}

# Python
class Node:
    def __init__(self, value):
        self.value = value
        self.next = None

class LinkedList:
    def __init__(self):
        self.head = None

    def insert(self, value):
        node = Node(value)
        if not self.head:
            self.head = node
            return
        current = self.head
        while current.next:
            current = current.next
        current.next = node

// C++
#include <iostream>

struct Node {
    int value;
    Node* next;

    Node(int v) : value(v), next(nullptr) {}
};

class LinkedList {
public:
    Node* head = nullptr;

    void insert(int value) {
        Node* node = new Node(value);
        if (!head) {
            head = node;
            return;
        }
        Node* current = head;
        while (current->next) {
            current = current->next;
        }
        current->next = node;
    }
};

// JavaScript
class Node {
  constructor(value) {
    this.value = value;
    this.next = null;
  }
}

class LinkedList {
  constructor() {
    this.head = null;
  }

  insert(value) {
    const node = new Node(value);
    if (!this.head) {
      this.head = node;
      return;
    }
    let current = this.head;
    while (current.next) {
      current = current.next;
    }
    current.next = node;
  }
}

Interactive Linked List Visualization

∅

List is empty. Insert a value to begin.

Size: 0

Node

Traversing

Found

Inserting

Removing

Note: Insert appends to end (O(n) for traversal, O(1) for actual insert). Remove/Search traverse from head until found.

enhanced.realWorldExamples.title

Music PlayersPlaylist Implementation

Music apps use doubly linked lists for next/previous song navigation.

Why? Efficient insertion/deletion without shifting elements.

Operating SystemsMemory Management

OS uses linked lists to track free memory blocks.

Why? Dynamic allocation without contiguous memory requirement.

Time Complexity

Singly linked lists allow constant-time operations at the head but require O(n) traversal for arbitrary inserts, removals, and searches.

Operation	Time	Why?
Create (n)	`O(n)`	Allocate n nodes and link them
Insert (anywhere)	`O(n)`	Traverse to target index then link new node
Remove (anywhere)	`O(n)`	Traverse to previous node and unlink target
Search	`O(n)`	Traverse nodes one by one
Access HEAD/Tail	`O(1)`	Head pointer is always available
Clear	`O(n)`	Visit all nodes and reset links

Note: Since nodes are scattered in memory, linked lists are great for dynamic sizes but cost O(n) when scanning for an index.

enhanced.complexityAnalysis.title

enhanced.complexityAnalysis.mathematicalTitle

Access requires traversal from head, visiting each node sequentially. For element at position k, we must traverse k nodes, giving O(k) which is O(n) in worst case.

🟢Best Case

O(1) for insertion/deletion at head. O(1) for access if element is at head.

🟡Average Case

O(n/2) = O(n) for random access and search operations.

🔴Worst Case

O(n) for access, search, and insertion/deletion at arbitrary positions.

💾Space Complexity

O(n) with additional pointer overhead per node (typically 8 bytes for next pointer on 64-bit systems).

⚡Cache Performance

Poor cache locality as nodes may be scattered in memory. Each access may cause a cache miss.

enhanced.codeWalkthrough.title

enhanced.codeWalkthrough.stepByStep

Each node contains data and a reference (pointer) to the next node. The 'next' pointer is initialized to null, indicating no following node yet.

class Node {
  constructor(data) {
    this.data = data;
    this.next = null;
  }
}

enhanced.practiceProblems.title

Reverse Linked List

easy

Reverse a singly linked list and return the new head.

Input:1 -> 2 -> 3 -> 4 -> 5

Output:5 -> 4 -> 3 -> 2 -> 1

enhanced.relatedTopics.related

Doubly Linked List Array

enhanced.relatedTopics.advanced

Hash Table Graph DFS

Continue Learning

Practice operations and explore implementations for singly linked lists.

enhanced.author.title

enhanced.author.writtenBy:enhanced.author.teamName

enhanced.author.reviewedBy:enhanced.author.reviewerName

enhanced.author.lastUpdated:January 28, 2026