Implement two stacks in an array Python

PROGRAM TO IMPLEMENT TWO STACKS IN AN ARRAY

class twoStacks:

      

    def __init__(self, n):     # constructor

        self.size = n

        self.arr = [None] * n

        self.top1 = -1

        self.top2 = self.size

          

    # Method to push an element x to stack1

    def push1(self, x):

          

        # There is at least one empty space for new element

        if self.top1 < self.top2 - 1 :

            self.top1 = self.top1 + 1

            self.arr[self.top1] = x

  

        else:

            print("Stack Overflow ")

            exit(1)

  

    # Method to push an element x to stack2

    def push2(self, x):

  

        # There is at least one empty space for new element

        if self.top1 < self.top2 - 1:

            self.top2 = self.top2 - 1

            self.arr[self.top2] = x

  

        else :

           print("Stack Overflow ")

           exit(1)

  

    # Method to pop an element from first stack

    def pop1(self):

        if self.top1 >= 0:

            x = self.arr[self.top1]

            self.top1 = self.top1 -1

            return x

        else:

            print("Stack Underflow ")

            exit(1)

  

    # Method to pop an element from second stack

    def pop2(self):

        if self.top2 < self.size:

            x = self.arr[self.top2]

            self.top2 = self.top2 + 1

            return x

        else:

            print("Stack Underflow ")

            exit()

  

# Driver program to test twoStacks class

ts = twoStacks(5)

ts.push1(5)

ts.push2(10)

ts.push2(15)

ts.push1(11)

ts.push2(7)

  

print("Popped element from stack1 is " + str(ts.pop1()))

ts.push2(40)

print("Popped element from stack2 is " + str(ts.pop2()))




OUTPUT:

Popped element from stack1 is 11
Popped element from stack2 is 40

CREDITS: https://www.geeksforgeeks.org/implement-two-stacks-in-an-array/