Add basic singly linked list implementation in both Objective-C and C (typedef struct)

[ruvalcaba18]

Summary

This pull request adds a foundational implementation of a singly linked list in two styles:

• ✅ Object-Oriented: using Objective-C classes (LinkedListNode)
• ✅ C-style: using typedef struct and manual memory management

These match the patterns and function examples shown in Cracking the Coding Interview, providing support for classic linked list problems.

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Objective-C Implementation Highlights

• LinkedListNode class:
  • appendToTail: – adds a new node to the end of the list
  • deleteNode: – removes the first occurrence of a node with a specific value
  • printList: – utility class method to print the contents of a list

All methods include documentation and mimic common patterns found in the book.

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C (typedef struct) Implementation Highlights

• Struct: LinkedListNode_C_Style
• Functions:
  • createNode(int value)
  • appendToTail(LinkedListNode_C_Style *head, int value)
  • deleteNode(LinkedListNode_C_Style *head, int value)
  • printList(LinkedListNode_C_Style *head)
  • freeList(LinkedListNode_C_Style *head)

This implementation helps reinforce pointer manipulation, memory handling (malloc / free), and basic data structure fundamentals — perfect for interview preparation in low-level environments.

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Motivation

The purpose of this addition is to provide:

• A dual-style reference (Objective-C and C) for beginners and advanced users
• A clear base for solving linked list problems such as:
  • Remove Duplicates
  • Delete Middle Node
  • Partition List
  • Detect Loop
  • Reverse List

This aligns directly with Chapter 2 of Cracking the Coding Interview.

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Happy to receive feedback or suggestions. Thanks for maintaining this repo!