Developing DS learning Basics I

Linear Data Structures

Sequence of data organized linearly or sequentially, where each element is added to its previous and next adjacents.

Array

An array is a series or list of variables in the memory block that have the same name and the same data type, but are differentiated with special numbers called #subscripts, also called index. The index is a number that indicates the position of the item.

For example, it could represent an employee identification list or a price list for items for sale.

It is widely used in various applications, such as:

• Storing data for processing
• Implementation of data structures such as #Filas and #Pilas
• Representing data in tables and arrays
• Creating dynamic data structures such as linked lists and trees

Array types

1-dimension array

Stores only one row of elements

Multi-dimensional array

Stores multiple rows of elements

Basic operations in the Arrays

Transversal

Visiting each element of an array in a specific order:

									
	def sequential(array):
		for element in array
			print(element)

	arr = [2, 4, 5, 10, 15, 3]
	sequential(arr)
									
								

									
	def reverse(array):
		for element in array[::-1]:
		print(element)

	arr = [2, 4, 5, 10, 15, 3]
	reverse(arr)
									
								

Insertion

Adding a new element to the array at a specific index, where we call the function to insert a specific value into the array on the desired line.

our array 2, 4, 5, 10, 15, 3 will receive the value 10 in position 3

									
	def insert(array, element, position):
		if position < 0 or position > len(array):
			print("Invalid position")
		else:
			array.insert(position, element)
	
	arr = [2, 4, 5, 10, 15, 3]
	insert(arr, 10, 3)
	print(arr)
									
								

Delete

Removing an array element from a specific index. Let's remove position 2 from arr

									
	def remove(array, index):
		if index < 0 or index >= len(array):
			print(“Invalid index”)
		else:
			array.pop(index)

	arr = [2, 4, 5, 10, 10, 15, 3]
	remove(arr, 2)
	print(arr)
									
								

Search

Finding the index of an array element. What happens if we look for index 4?

									
	def search(array, value):
		for i in range(len(array)):
			if array[i] == value:
				return i
		return -1  

	arr = [2, 4, 10, 10, 15, 3]
	index = search(arr, 4)  
	value = search(arr, index)

	print(f"Value found at position {index} is {value}")

									
								

Update

updates the value of an array at the given index and returns a message confirming the change. If the index is invalid, it reports the error and keeps the array unchanged.

Let's update position 3with value 15.

									
	def update(array, index, new_value):
		if 0 <= index < len(array):
			array[index] = new_value
			return new_value

	arr = [2, 4, 10, 10, 15, 3]
	index = 3
	new_value = 15

	update(arr, index, new_value)

	print(f"Element at index {index} updated to {new_value}", arr)

									
								

Update

updates the value of an array at the given index and returns a message confirming the change. If the index is invalid, it reports the error and keeps the array unchanged.

									
	def display(array):
		return array

	arr = [2, 4, 10, 10, 15, 3]
	message = display(arr)
	print(message)

									
								

References

1. Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, and Clifford Stein. Introduction to Algorithms, Third Edition (3rd. ed.). The MIT Press, 2009.

2. GONZAGA DE OLIVEIRA, S. L. Algoritmos e seus fundamentos. Lavras: Editora UFLA, 2011.

3. SZWARCFITER, Jayme L.; MARKENZON, Lilian. Estruturas de Dados e Seus Algoritmos. Rio de Janeiro: LTC, 2010. E-book. ISBN 978-85-216-2995-5.