Stack
Stack is a subset of list(which is extended from Vector in Java) base on the LIFO ordering.
In Java, the Stack class provides five operations to achieve it: https://docs.oracle.com/javase/7/docs/api/java/util/Stack.html
Push: pushes an element on the top of this stack
Pop: removes the element from the top of the stack
Peek: gets the top element of the stack
Empty: boolean empty() returns true if the stack is empty
Search: int search, searches for element in the stack, returns its offset from the top if it's found