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📦 Array

Introduction​

An array is a data structure that stores a fixed-size sequence of elements of the same type in contiguous memory locations.

Key Properties​

  • Indexed: Each element can be accessed directly by its index
  • Fixed size: The size is defined at creation and cannot be changed
  • Homogeneous: All elements are of the same type

Common Operations​

  • Access: O(1) - Direct access by index
  • Update: O(1) - Direct update by index
  • Search: O(n) - Linear search for an element
  • Insert/Delete: O(n) - May require shifting elements

Example (Python)​

# Creating an array
arr = [10, 20, 30, 40, 50]

# Accessing elements
print(arr[2])  # Output: 30

# Updating elements
arr[1] = 25
print(arr)  # Output: [10, 25, 30, 40, 50]

# Searching for an element
if 40 in arr:
    print("Found!")

# Inserting an element (at the end)
arr.append(60)

# Deleting an element (by value)
arr.remove(30)
print(arr)  # Output: [10, 25, 40, 50, 60]

When to Use Arrays​

  • When you need fast, direct access to elements by index
  • When the number of elements is known and fixed
  • For implementing other data structures (stacks, queues, etc.)

Limitations​

  • Fixed size (in most languages)
  • Insertion and deletion can be costly (O(n))
  • All elements must be of the same type
  • Dynamic Array (List in Python, Vector in C++): Resizable version of an array
  • Linked List: Allows efficient insertions/deletions but slower access