stack-of-plates.py

"""
cracking coding interview page #99s

Design a stack of plates. 
Set of stacks is composed of many stacks and should create a new stack once the previous once exceeds the capacity
push(),pop() should behave identically to a single stack. 



"""


class Setofstacks():
    def __init__(self) -> None:
        self.stacks=[]
        self.top = None
        self.threshold = 1
    def isempty(self):
        return self.top == None
    def createStacks(self,data):
        l = list()
        l.append(data)
        self.stacks.append(l)
        self.top = self.stacks[-1][-1]
        return
    def push(self,data):
        if self.top == None or len(self.stacks[-1])>=self.threshold:
            #stack is empty
            self.createStacks(data)
        else: 
            #in middle of stack
            self.stacks[-1].append(data)
            self.top = self.stacks[-1][-1]
        return
    
    def pop(self):
        if not self.isempty():
            if len(self.stacks[-1]) <=1:
                #last list has 1 or empty list ex:[[1,2],[3]] or [[1,2],[]]
                #so delete entire list
                self.stacks.pop()

                if len(self.stacks) == 0:
                    self.top = None
                else:
                    self.top = self.stacks[-1][-1]

            else:
                #last list has  more than 1 element. ex:[[1,2][3,4]]
                self.stacks[-1].pop() # ex:[[1,2][3]]
                self.top = self.stacks[-1][-1]
        else:
            print("stack is empty")
        return

    def peek(self):
        return self.top
    def print(self):
        print(self.stacks)
    def popAt(self,index):
        """
        delete element in given index. 
        ex: [[1,2],[3,4]] 
        popat(0)-> [[2],[3,4]]
        push(5) ->[5,2][3,4]]
        popat(0) ->[[2][3,4]]

        """
        

        pass
obj = Setofstacks()
obj.push(1)
obj.push(2)
obj.push(3)
obj.push(4)
obj.print()
print("top element is ",obj.peek())
obj.pop()
obj.print()
print("top element is ",obj.peek())

obj.push(5)
obj.push(6)
obj.push(7)
obj.push(8)
obj.print()
print("top element is ",obj.peek())

obj.pop()
obj.print()
print("top element is ",obj.peek())
obj.pop()
obj.print()
print("top element is ",obj.peek())
obj.pop()
obj.print()
print("top element is ",obj.peek())
obj.pop()
obj.pop()
obj.pop()
obj.print()
print("top element is ",obj.peek())
obj.pop()
obj.print()
print("top element is ",obj.peek())