🟢 剑指 Offer 09. 用两个栈实现队列

LeetCode 提示

题目难度 简单

原题链接 🔗 leetcode

题解 1.py

class CQueue:      def __init__(self):        self.stackOrd, self.stackRev = [], []

    def appendTail(self, value: int) -> None:        self.stackOrd.append(value)

    def deleteHead(self) -> int:        if len(self.stackOrd) == 0:            return -1        while self.stackOrd:            self.stackRev.append(self.stackOrd.pop())        res = self.stackRev.pop()        while self.stackRev:            self.stackOrd.append(self.stackRev.pop())        return res



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

题解 2_更省事.py

# 并不用实时保留完整队列，把stack1和stack2理解为队列的前半部和后半部就好class CQueue:      def __init__(self):        self.stack1, self.stack2 = [], []

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

    def deleteHead(self) -> int:        if len(self.stack2) == 0:            while self.stack1:                self.stack2.append(self.stack1.pop())        if len(self.stack2) == 0:            return -1        return self.stack2.pop()


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