Create a customized data structure which evaluates functions in O(1)

Create a customized data structure such that it has functions :- 

• GetLastElement(); 
• RemoveLastElement(); 
• AddElement() 
• GetMin()

All the functions should be of O(1)

Question Source : amazon interview questions

Approach :

1. create a custom stack of type structure with two elements, (element, min_till_now) 
2. implement the functions on this custom data type 

Implementation:

5 inserted successfully
7 inserted successfully
3 inserted successfully
min element :: 3
removed successfully
2 inserted successfully
9 inserted successfully
Last element :: 9
0 inserted successfully
min element :: 0
removed successfully
11 inserted successfully
min element :: 2

Time complexity: Each function runs in O(1)
Auxiliary space: O(n) for stack