[LeetCode] Implement Stack using Queues (Python)

 

 

from collections import deque

class MyStack:

    def __init__(self):
        self.stack1 = deque()
        self.stack2 = deque()

    def push(self, x: int) -> None:
        self.stack1.append(x)

    def pop(self) -> int:
        
        while len(self.stack1) > 1:
            temp = self.stack1.popleft()
            self.stack2.append(temp)
            
        if len(self.stack1) == 1:
            answer = self.stack1.popleft()
            self.stack1, self.stack2 = self.stack2, self.stack1
        return answer

    def top(self) -> int:
        return self.stack1[-1]

    def empty(self) -> bool:
        return False if self.stack1 else True


# Your MyStack object will be instantiated and called as such:
# obj = MyStack()
# obj.push(x)
# param_2 = obj.pop()
# param_3 = obj.top()
# param_4 = obj.empty()