Amortized time of dynamic array

Question

As a simple example, in a specific implementation of the dynamic array, we double the size of the array each time it fills up. Because of this, array reallocation may be re

Answer 1

Yes, these two statements say the same thing, Wiki just explains it more thoroughly.

Answer 2

Amortized basically means average per number of operations.

So, if you have an array of n, you need to insert n+1 items until you'll need the reallocation.

So, you've done n inserts which each one of them took O(1), and another insert that took O(n), so in total you've got n+1 actions that cost you 2n operations .

2n / n+1  ~= 1 

That's why the Amortized time is still O(1)