Can you explain how the Capacity Array data structure is implemented and how it manages its capacity in memory?

Capacity Array is a data structure that manages an array with allocated memory capacity, allowing efficient addition of elements without frequent reallocation.

How it works:

• Initially, an array with a certain capacity is allocated.
• When adding elements, if the current size (count) is less than the capacity, the element is simply added.
• If the size reaches the capacity, the capacity is increased (usually doubled), a new larger array is allocated, and data is copied over.

This approach reduces the number of memory allocation and copying operations, improving performance during dynamic array growth.

Example in Swift:

var array = [Int]()
array.reserveCapacity(10) // allocate capacity for 10 elements

for i in 1...15 {
    array.append(i) // when reaching 10 elements, capacity will automatically increase
}

Here, reserveCapacity sets the initial capacity, and as elements are added, the capacity automatically expands.