编程语言
首页 > 编程语言> > python 用两个栈实现一个队列

python 用两个栈实现一个队列

作者:互联网

| 两个栈实现队列

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]

|题解

class CQueue:

    def __init__(self):
        self.stack1 = list()
        self.stack2 = list()

    def appendTail(self, value: int) -> None:
        while self.stack1:
            self.stack2.append(self.stack1.pop())
        self.stack1.append(value)

        while self.stack2:
            self.stack1.append(self.stack2.pop())

    def deleteHead(self) -> int:
        if self.stack1:
            return self.stack1.pop()
        else:
            return -1

# Your CQueue object will be instantiated and called as such:
# obj = CQueue()
# obj.appendTail(value)
# param_2 = obj.deleteHead()

标签:deleteHead,appendTail,python,self,队列,null,实现,stack1
来源: https://blog.csdn.net/python_tian/article/details/121594051