Stack

• "Last In, First Out" (LIFO)

• push(element): Add element to the top of the Stack

  top(): Look at the element at the top of the Stack

  pop(): Remove the element at the top of the Stack

• Use Deque to implement Stack

• Same as queue, the back structure can be Linked List or Circular Array

• How to use circular array to create a stack?

  Ans: Keep a int top, recording the index of the top element in stack
  

• How to use Linked List to create a stack?

  Ans: Keep a pointer top, point to the top element in stack
  

• DFS

REFERENCE: stepik 2.8