python 数据结构之队列和栈

用Python实现队列和栈

队列

1. 先进先出
2. 只能从队列末尾插入数据
3. 只能从队列头部取出数据

用python实现队列

class Queue(object):
    def __init__(self):
        self.data_list = []

    def init_queue(self):
        self.data_list = []

    def insert(self, data):
        self.data_list.append(data)

    def pop(self):
        if len(self.data_list) == 0:
            return None
        data = self.data_list[0]
        del self.data_list[0]
        return data

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


queue = Queue()
print(queue.size())
queue.insert(1)
queue.insert(2)
queue.insert(3)
head = queue.pop()
print(head)
head = queue.pop()
print(head)
head = queue.pop()
print(head)

输出：

0
1
2
3
None

栈

1. 后进先出
2. 只能从尾部插入数据
3. 只能从尾部取数据。

用python实现栈

class Stack(object):
    def __init__(self):
        self.data_stack = []

    def init_stack(self):
        self.data_stack = []

    def insert(self, data):
        self.data_stack.append(data)

    def pop(self):
        if len(self.data_stack) == 0:
            return None
        data = self.data_stack[-1]
        del self.data_stack[-1]
        return data

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


stack = Stack()
stack.insert(1)
stack.insert(2)
stack.insert(3)
print(stack.size())
tail = stack.pop()
print(tail)
tail = stack.pop()
print(tail)
tail = stack.pop()
print(tail)
tail = stack.pop()
print(tail)

输出：

3
3
2
1
None