232. Implement queue using stacks
[Easy] “Implement a queue using stacks.."
Python3:
class MyQueue:
def __init__(self):
"""
Initialize your data structure here.
"""
self.stack_1 = []
self.stack_2 = []
def push(self, x: int) -> None:
"""
Push element x to the back of queue.
"""
self.stack_1.append(x)
def pop(self) -> int:
"""
Removes the element from in front of queue and returns that element.
"""
for _ in range(len(self.stack_1)):
stack_pop = self.stack_1.pop()
self.stack_2.append(stack_pop)
res = self.stack_2.pop()
for _ in range(len(self.stack_2)):
stack_pop = self.stack_2.pop()
self.stack_1.append(stack_pop)
return res
def peek(self) -> int:
"""
Get the front element.
"""
return self.stack_1[0]
def empty(self) -> bool:
"""
Returns whether the queue is empty.
"""
return not self.stack_1
# 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()