Python数据结构-栈、队列

由于 Python 基础数据类型封装得比较强大，实现栈和队列显得很容易

1. Python 实现栈

class Stack(object):

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

    def is_empty(self):
        return self.items == []

    def push(self, item):
        self.items.append(item)

    def pop(self):
        self.items.pop()

    def peek(self):
        """返回栈顶元素"""
        return self.items[len(self.items)-1]

    def size(self):
        return len(self.items)


if __name__ == '__main__':
    stack = Stack()
    print('栈是否为空:', stack.is_empty())
    stack.push(4)
    stack.push(8)
    stack.push(1)
    print(stack.peek())
    stack.pop()
    print('栈是否为空:', stack.is_empty())
    print(stack.size())

2. Python 实现队列

class Queue(object):

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

    def is_empty(self):
        return self.items == []

    def enqueue(self, item):
        self.items.insert(0, item)

    def dequeue(self):
        self.items.pop()

    def size(self):
        return len(self.items)


if __name__ == '__main__':
    queue = Queue()
    print('队列是否为空:', queue.is_empty())
    queue.enqueue(10)
    queue.enqueue(8)
    queue.enqueue(4)
    queue.dequeue()
    print(queue.size())

3. Python 实现双端队列

class Deque(object):

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

    def is_empty(self):
        return self.items == []

    def add_front(self, item):
        self.items.insert(0, item)

    def add_rear(self, item):
        self.items.append(item)

    def remove_front(self):
        self.items.pop(0)

    def remove_rear(self):
        self.items.pop()

    def size(self):
        return len(self.items)

if __name__ == '__main__':
    deque = Deque()
    print('双端队列是否为空:', deque.is_empty())
    deque.add_front(4)
    deque.add_rear(1)
    deque.add_front(6)
    deque.add_rear(8)
    print(deque.size())
    deque.remove_rear()
    print(deque.size())