KAIST 산업및시스템공학과 문일철_ 데이터 구조 및 분석 수업을 참고하여 작성하였습니다

ch_3_5 Stack

Stack

1. Structure of Stack
    : linear like linked lists (A variation of a singly linked list)
    : Voluntarily giving up
        - Access to the middle in the linked list
        - Only accesses to the first instance in the list
    : The first instance in the list 
        = The top instacne in the stack
    : is iserted or removed from the stack from one end called the 'top' of the stack
    : is called Last-In-First-Out (LIFO)

2. Operation of Stack
    - Push
        = Insert an instance at the fist in the linked list
        = Put an instance at the top in the stack
    - Pop
        = Remove and return an instance at the fist in the linked list
        = Remove and return an instance at the top in the stack

3. Implementation of Stack
    - Python code of a stack
      - Utilizing a singly linked list
      - To pop an instance (I retrieval count)
      - To push an instnace (I retrieval count)

from edu.kaist.seslab.ie362.week3.SinglyLinkedList import SinglyLinkedList

class Stack(object) :
    lstInstance = SinglyLinkedList()
    def pop(self):
        return self.lstInstance.removeAt(0)
    def push(self):
        self.lstInstance.insertAt(value, 0)

stack =  Stack()
stack.push('a')
stack.push('b')
stack.push('c')

print(stack.pop())
print(stack.pop())
print(stack.pop())

# c
# b
# a

4. Balancing Symbols
    - Algorithm for the balanced symbol checking
      - Mack an empty stack
      - read symbols until end of formula
        - if 여는 symbol 있으면 push
        - if 닫는 symbol 있으면, if stack is empty 면 error
    - At the end of the of formula if the stack is not empty report an error