算法刷题

剑指 Offer 09. 用两个栈实现队列

class CQueue:
    def __init__(self):
        self.A, self.B = [], []

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

    def deleteHead(self) -> int:
        if self.B: return self.B.pop()
        if not self.A: return -1
        while self.A:
            self.B.append(self.A.pop())
        return self.B.pop()

class CQueue:

    def __init__(self):
        self.queue = []

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

    def deleteHead(self) -> int:
        if len(self.queue) > 0:
            return self.queue.pop(0)
            
        else:
            return -1

剑指 Offer 30. 包含min函数的栈

自己写的

class MinStack:

    def __init__(self):
        """
        initialize your data structure here.
        """
        self.stack = []


    def push(self, x: int) -> None:
        self.stack.append(x)


    def pop(self) -> None:
        if len(self.stack) > 0:
            return self.stack.pop()


    def top(self) -> int:
        if len(self.stack) > 0:
             return self.stack[-1]


    def min(self) -> int:
        if len(self.stack) > 0:
            return min(self.stack)

别人的

class MinStack:
    def __init__(self):
        self.A, self.B = [], []

    def push(self, x: int) -> None:
        self.A.append(x)
        if not self.B or self.B[-1] >= x:
            self.B.append(x)

    def pop(self) -> None:
        if self.A.pop() == self.B[-1]:
            self.B.pop()

    def top(self) -> int:
        return self.A[-1]

    def min(self) -> int:
        return self.B[-1]