用两个栈实现一个队列。队列的声明如下,请实现它的两个函数 appendTail 和 deleteHead ,分别完成在队列尾部插入整数和在队列头部删除整数的功能。(若队列中没有元素,deleteHead 操作返回 -1 )
示例 1:
输入:
["CQueue","appendTail","deleteHead","deleteHead"]
[[],[3],[],[]]
输出:[null,null,3,-1]
示例 2:
输入:
["CQueue","deleteHead","appendTail","appendTail","deleteHead","deleteHead"]
[[],[],[5],[2],[],[]]
输出:[null,-1,null,null,5,2]
提示:
1 <= values <= 10000 最多会对 appendTail、deleteHead 进行 10000 次调用
class CQueue:
def __init__(self):
self.queueListOut = []
self.queueListTemp = []
def appendTail(self, value: int) -> None:
self.queueListTemp.append(value)
def deleteHead(self) -> int:
if len(self.queueListOut) <= 0 and len(self.queueListTemp)<= 0: return -1
if len(self.queueListOut) != 0:
return self.queueListOut.pop()
while len(self.queueListTemp) != 0:
self.queueListOut.append(self.queueListTemp.pop())
return self.queueListOut.pop()
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