class MidStack:
def __init__(self):
self.stac = ArrayStack()
self.dque = ArrayDeque()
def __len__(self):
return len(self.stac) + len(self.dque)
def is_empty(self):
return len(self.stac) == 0 and len(self.dque) == 0
def top(self):
if (self.is_empty()):
raise Exception("Stack is empty")
return self.dque.last()
def push(self, val):
if self.is_empty():
self.stac.push(val)
elif len(self) % 2 == 0:
self.stac.push(self.dque.first())
self.dque.dequeue_first()
self.dque.enqueue_last(val)
elif len(self) % 2 == 1:
self.dque.enqueue_last(val)
def pop(self):
if self.is_empty():
raise Exception("Stack is empty")
else:
if len(self.stac) == 1 and len(self.dque) == 0:
return self.stac.pop()
elif len(self) % 2 == 0:
return self.dque.dequeue_last()
elif len(self) % 2 == 1:
self.dque.enqueue_first(self.stac.top())
self.stac.pop()
return self.dque.dequeue_last()
def mid_push(self, val):
if len(self) % 2 == 0:
self.stac.push(val)
else:
self.dque.enqueue_first(val)
class MidStack:
def __init__(self):
self.top_deque = ArrayDeque()
self.bottom_stack = ArrayStack()
def __len__(self):
return len(self.top_deque) + len(self.bottom_stack)
def is_empty(self):
return len(self) == 0
def push(self, e):
if (len(self) % 2 == 1): # even len
# top deque has one more than bottom stack
# then shift last deque member to top of stack and enqueue first val to deque
last_deque = self.top_deque.last()
self.bottom_stack.push(last_deque)
self.top_deque.dequeue_last()
self.top_deque.enqueue_first(e)
def top(self):
if (self.is_empty()):
raise Exception("Stack is empty")
return self.top_deque.first()
def pop(self):
if (self.is_empty()):
raise Exception("Stack is empty")
else:
if (len(self) % 2 == 0): # top and bottom have same
# make sure that the top always has one more than the bottom
top_stack = self.bottom_stack.pop()
self.top_deque.enqueue_last(top_stack)
return self.top_deque.dequeue_first()
def mid_push(self, e):
if (len(self) % 2 == 0): # top and bottom have same num elem
self.top_deque.enqueue_last(e)
else: # top has one more than bottom, make even
self.bottom_stack.push(e)