@@ -281,48 +281,54 @@ class MyQueue {
281281
282282Python:
283283``` python
284- # 使用两个栈实现先进先出的队列
285284class MyQueue :
285+ 286286 def __init__ (self
287287 """
288- Initialize your data structure here.
288+ in主要负责push,out主要负责pop
289289 """
290- self .stack1 = list ()
291- self .stack2 = list ()
290+ self .stack_in = []
291+ self .stack_out = []
292+ 292293
293294 def push (self x : int ) -> None :
294295 """
295- Push element x to the back of queue.
296+ 有新元素进来,就往in里面push
296297 """
297- # self.stack1用于接受元素
298- self .stack1.append(x)
298+ self .stack_in.append(x)
299+ 299300
300301 def pop (self int :
301302 """
302- Removes the element from in front of queue and returns that element.
303+ 1. 检查如果out里面元素,则直接pop
304+ 2. 如果out没有元素,就把in里面的元素(除了第一个)依次pop后装进out里面
305+ 3. 直接把in剩下的元素pop出来,就是queue头部的
303306 """
304- # self.stack2用于弹出元素,如果self.stack2为[],则将self.stack1中元素全部弹出给self.stack2
305- if self .stack2 == []:
306- while self .stack1:
307- tmp = self .stack1.pop()
308- self .stack2.append(tmp)
309- return self .stack2.pop()
307+ if self .stack_out:
308+ return self .stack_out.pop()
309+ else :
310+ for i in range (1 , len (self .stack_in)):
311+ self .stack_out.append(self .stack_in.pop())
312+ return self .stack_in.pop()
313+ 310314
311315 def peek (self int :
312316 """
313- Get the front element.
317+ 1. 查out有没有元素,有就把最上面的返回
318+ 2. 如果out没有元素,就把in最下面的返回
314319 """
315- if self .stack2 == [] :
316- while self .stack1:
317- tmp = self .stack1.pop()
318- self .stack2.append(tmp)
319- return self .stack2[ - 1 ]
320+ if self .stack_out :
321+ return self .stack_out[ - 1 ]
322+ else :
323+ return self .stack_in[ 0 ]
324+ 320325
321326 def empty (self bool :
322327 """
323- Returns whether the queue is empty.
328+ 只要in或者out有元素,说明队列不为空
324329 """
325- return self .stack1 == [] and self .stack2 == []
330+ return not (self .stack_in or self .stack_out)
331+ 326332```
327333
328334
0 commit comments