Implement the following operations of a queue using stacks.
Example:
MyQueue queue = new MyQueue(); queue.push(1); queue.push(2); queue.peek(); // returns 1 queue.pop(); // returns 1 queue.empty(); // returns false
Notes:
push to top, peek/pop from top, size, and is empty operations are valid.
class MyQueue:
def __init__(self):
"""
Initialize your data structure here.
"""
self.stack1 = []
self.stack2 = []
def push(self, x):
"""
Push element x to the back of queue.
:type x: int
:rtype: void
"""
self.stack1.append(x)
def dump_data(self):
if not self.stack2:
while self.stack1:
self.stack2.append(self.stack1.pop())
def pop(self):
"""
Removes the element from in front of queue and returns that element.
:rtype: int
"""
self.dump_data()
return self.stack2.pop()
def peek(self):
"""
Get the front element.
:rtype: int
"""
self.dump_data()
return self.stack2[-1]
def empty(self):
"""
Returns whether the queue is empty.
:rtype: bool
"""
return not self.stack1 and not self.stack2
# 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()
leetcode 232. Implement Queue using Stacks
原文：https://www.cnblogs.com/bonelee/p/9180422.html