implement-queue-using-stacks.py

"""
https://leetcode.com/submissions/detail/149348209/


Implement the following operations of a queue using stacks.


push(x) -- Push element x to the back of queue.


pop() -- Removes the element from in front of queue.


peek() -- Get the front element.


empty() -- Return whether the queue is empty.


Notes:

You must use only standard operations of a stack -- which means only push to top, peek/pop from top, size, and is empty operations are valid.
Depending on your language, stack may not be supported natively. You may simulate a stack by using a list or deque (double-ended queue), as long as you use only standard operations of a stack.
You may assume that all operations are valid (for example, no pop or peek operations will be called on an empty queue).

"""


class MyQueue:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.queue = []
        

    def push(self, x):
        """
        Push element x to the back of queue.
        :type x: int
        :rtype: void
        """
        self.queue.append(x)
        

    def pop(self):
        """
        Removes the element from in front of queue and returns that element.
        :rtype: int
        """
        return self.queue.pop(0)
        

    def peek(self):
        """
        Get the front element.
        :rtype: int
        """
        return self.queue[0]
        

    def empty(self):
        """
        Returns whether the queue is empty.
        :rtype: bool
        """
        return len(self.queue) == 0
        


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