Implement the following operations of a stack using queues.
push(x) -- Push element x onto stack.
pop() -- Removes the element on top of the stack.
top() -- Get the top element.
empty() -- Return whether the stack is empty.
Example:
又到了作弊神预言Python的强项
MyStack stack = new MyStack();
stack.push(1);
stack.push(2);
stack.top(); // returns 2
stack.pop(); // returns 2
stack.empty(); // returns false
Notes:
You must use only standard operations of a queue -- which means only push to back, peek/pop from front, size, and is empty operations are valid.
Depending on your language, queue may not be supported natively. You may simulate a queue by using a list or deque (double-ended queue), as long as you use only standard operations of a queue.
You may assume that all operations are valid (for example, no pop or top operations will be called on an empty stack).
```
class Stack(object):
## 解题方案
> 思路 1
******- 时间复杂度: Push O(N) + Pop O(1) ******- 空间复杂度: O(N)******
```python
classMyStack:
def__init__(self):
"""
initialize your data structure here.
Initialize your data structure here.
"""
self.lst = []
self.queue=collections.deque()
def push(self, x):
defpush(self,x:int)->None:
"""
:type x: int
:rtype: nothing
Push element x onto stack.
"""
self.lst.append(x)
self.queue.append(x)
for_inrange(len(self.queue)-1):
self.queue.append(self.queue.popleft())
def pop(self):
defpop(self)->int:
"""
:rtype: nothing
Removes the element on top of the stack and returns that element.