What is vector?
Vector is a
dynamic arrary in C++ STL. It allows us to find an element with
O(1), append or remove last element average complexity is O(1) and delete
random element with O(N).
Vector uses a technique named
* If my array is not full, we add new element at end of array.
* If my array is full:
+ Allocate an new memory = 2 * Length of current array
+ Copy current array to new array.
+ Append new element to new array.