Tumpukan (stack) dan Antrean (Queue) | Berpikir Komputasional kelas X

Introduction

This tutorial explores the concepts of stacks and queues, essential data structures in computer science. Understanding these structures is crucial for students in computational thinking, particularly for those in high school-level informatics. We will break down both concepts, their implementations, and practical applications.

Step 1: Understanding Stacks

A stack is a collection of elements that follows the Last In, First Out (LIFO) principle. This means that the last element added to the stack is the first one to be removed.

Key Characteristics

• Push Operation: Adding an element to the top of the stack.
• Pop Operation: Removing the top element from the stack.
• Peek Operation: Viewing the top element without removing it.

Practical Advice

• Visualize a stack as a pile of plates; you can only add or remove the top plate.
• Use stacks for scenarios like undo mechanisms in applications or call history in programming.

Step 2: Exploring Queues

A queue is a collection of elements that follows the First In, First Out (FIFO) principle. This means that the first element added to the queue is the first one to be removed.

Key Characteristics

• Enqueue Operation: Adding an element to the end of the queue.
• Dequeue Operation: Removing the front element from the queue.
• Front Operation: Viewing the front element without removing it.

Practical Advice

• Think of a queue as a line of people waiting for service; the first person in line is the first to be served.
• Queues are commonly used in scheduling processes, like print jobs or task management.

Step 3: Implementing Stacks and Queues

Stack Implementation

1. Using an Array:

   • Declare an array to hold stack elements.
   • Maintain a pointer or index to track the top of the stack.
   • Use push and pop functions to manipulate the stack.

   stack = []
   def push(element):
       stack.append(element)
   
   def pop():
       return stack.pop() if stack else None
   

Queue Implementation

1. Using an Array:

   • Declare an array to hold queue elements.
   • Maintain pointers for the front and rear of the queue.
   • Use enqueue and dequeue functions to manipulate the queue.

   queue = []
   def enqueue(element):
       queue.append(element)
   
   def dequeue():
       return queue.pop(0) if queue else None
   

Step 4: Applications of Stacks and Queues

• Stacks:

  • Used in backtracking algorithms (e.g., maze solving).
  • Implementing function calls in programming languages (call stack).

• Queues:

  • Managing tasks in a multi-threaded environment.
  • Handling requests in web servers.

Conclusion

Stacks and queues are fundamental data structures that enhance the efficiency of algorithms and applications. By mastering their concepts and implementations, you can solve various computational problems effectively. As a next step, practice coding these structures and explore their applications in real-world scenarios.