Solution to LeetCode #232: Implement Queue using Stacks (Python)
This is an easy LeetCode problem
Implement a first in first out (FIFO) queue using only two stacks. The implemented queue should support all the functions of a normal queue (
void push(int x)Pushes element x to the back of the queue.
int pop()Removes the element from the front of the queue and returns it.
int peek()Returns the element at the front of the queue.
trueif the queue is empty,
- You must use only standard operations of a stack, which means only
push to top,
peek/pop from top,
is emptyoperations are valid.
- Depending on your language, the stack may not be supported natively. You may simulate a stack using a list or deque (double-ended queue) as long as you use only a stack’s standard operations.
Python’s straightforward solution
Python makes this challenge very easy. Pretty much every operation is natively supported.
Initialize the class
__init__ function, set an instance variable that will hold all of our data.
self._fifo = 
When a class gets instantiated (in this case by calling
__init__() function gets executed. Setting an instance variable saves this data to the created instance and allows you to access the
self._fifo variable from other class functions.
push adds an item to the end of the queue.
push-ing to a queue is natively supported in Python via the
def push(self, x: int) -> None: