Special Stack Python

PROGRAM TO DESIGN AND IMPLEMENT SPECIAL STACK DATA STRUCTURE

class stack:

 

  def __init__(self):

 

    self.array = []

    self.top = -1

    self.max = 100 

 

  # Stack's member method to check

  # if the stack is iempty

  def isEmpty(self):

 

    if self.top == -1:

      return True

    else:

      return False 

 

  # Stack's member method to check

  # if the stack is full 

  def isFull(self): 

     

    if self.top == self.max - 1:

      return True

    else:

      return False  

 

  # Stack's member method to

  # insert an element to it  

 

  def push(self, data):

 

    if self.isFull():

      print('Stack OverFlow')

      return

    else:

      self.top += 1

      self.array.append(data)    

 

  # Stack's member method to

  # remove an element from it

  def pop(self):

 

    if self.isEmpty():

      print('Stack UnderFlow')

      return

    else:

      self.top -= 1

      return self.array.pop()

 

# A class that supports all the stack 

# operations and one additional

# operation getMin() that returns the

# minimum element from stack at

# any time.  This class inherits from

# the stack class and uses an

# auxiliarry stack that holds

# minimum elements 

class SpecialStack(stack):

 

  def __init__(self):

    super().__init__()

    self.Min = stack() 

 

  # SpecialStack's member method to

  # insert an element to it. This method

  # makes sure that the min stack is also

  # updated with appropriate minimum

  # values

  def push(self, x):

 

    if self.isEmpty():

      super().push(x)

      self.Min.push(x)

    else:

      super().push(x)

      y = self.Min.pop()

      self.Min.push(y)

      if x <= y:

        self.Min.push(x)

      else:

        self.Min.push(y) 

 

  # SpecialStack's member method to 

  # remove an element from it. This

  # method removes top element from

  # min stack also.

  def pop(self):

 

    x = super().pop()

    self.Min.pop()

    return x 

 

  # SpecialStack's member method

  # to get minimum element from it.

  def getmin(self):

 

    x = self.Min.pop()

    self.Min.push(x)

    return x

 

# Driver code

if __name__ == '__main__':

   

  s = SpecialStack()

  s.push(10)

  s.push(20)

  s.push(30)

  print(s.getmin())

  s.push(5)

  print(s.getmin())




OUTPUT:

10
5

CREDITS: https://www.geeksforgeeks.org/design-and-implement-special-stack-data-structure/