How to estimate the time complexity of the operation of removing an element from an array?

The time complexity of removing an element from an array depends on the array type and the removal method:

• In a standard array (e.g., Array in Swift), removing an element by index requires shifting all subsequent elements to the left to fill the "gap." This results in O(n), where n is the number of elements after the removed one.

• If the last element is removed, the operation is usually performed in O(1), as no shifting is needed.

• In the case of dynamic arrays (e.g., ArrayList in Java or NSMutableArray in Objective-C), the situation is similar — removing from the middle requires shifting elements.

Example:

var array = [1, 2, 3, 4, 5]
array.remove(at: 2) // removes the element at index 2 (number 3)
// After removal, elements 4 and 5 shift one position to the left

Thus, in general, removing an element from an array is an operation with a time complexity of O(n).