getmin.py

class Node:
    def __init__(self, value):
        self.value = value
        self.next = None

    def __str__(self):
        return 'Node ({})'.format(self.value)

    __repr__ = __str__


class Stack:
    def __init__(self):
        self.top = None
        self.count = 0
        self.minimum = None

    def __str__(self):
        temp = self.top
        out = []
        while temp:
            out.append(str(temp.value))
            temp = temp.next
        out = '\n'.join(out)
        return('Top {} \n\nStack : \n{}'.format(self.top.out))

    def getMin(self):
        if self.top is None:
            return "Stack is empty"
        else:
            print("Minimum Element in the stack is: {}" .format(self.minimum))

    def isEmpty(self):
        if self.top == None:
            return True
        else:
            return False

    def __len__(self):
        self.count = 0
        tempNode = self.top
        while tempNode:
            tempNode = tempNode.next
            self.count += 1
        return self.count

    def peek(self):
        if self.top is None:
            print('Stack is Empty')
        else:
            if self.top.value < self.minimum:
                print('Top Most Element is : {}'.format(self.minimum))
            else:
                print('Top Most Element is : {}'.format(self.top.value))

    def push(self,value):
        if self.top is None:
            self.top = Node(value)
            self.minimum = value

        elif value < self.minimum:
            temp = (2 * value) - self.minimum
            new_node = Node(temp)
            new_node.next = self.top
            self.top = new_node
            self.minimum = value
        else:
            new_node = Node(value)
            new_node.next = self.top
            self.top = new_node
        print('Number Inserted : {} '.format(value))

    def pop(self):
        if self.top is None:
            print('Stack is empty')
        else:
            removedNode = self.top.value
            self.top = self.top.next
            if removedNode < self.minimum:
                print("Top Most Element Removed :{} " .format(self.minimum))
                self.minimum = ( ( 2 * self.minimum ) - removedNode )
            else:
                print ("Top Most Element Removed : {}" .format(removedNode))


#Driver Class
stack = Stack()
 
stack.push(3)
stack.push(5)
stack.getMin()
stack.push(2)
stack.push(1)
stack.getMin()    
stack.pop()
stack.getMin()
stack.pop()
stack.peek()