Bc-數組-Stack

1.棧，堆棧，先進後出

2.棧的幾個操做：

> 入棧，push

> 出棧，pop

> 獲取棧頂元素，peek

> 獲取棧中共有元素個數，getSize

> 是否爲空，isEmpty

#coding:utf-8
class Stack:
    """
    自定義棧
    """
    _arr = []
    capacity = 0
    size = 0
    def __init__(self, capacity=10):
        self.capacity = capacity

    def push(self, element):
        self._arr.append(element)
        self.size += 1
    def pop(self):
        if self.size <= 0:
            raise Exception("Stack is empty.")
        del self._arr[self.size - 1]
        return self.size - 1
    def peek(self):
        pass

    def get_size(self):
        pass

    def is_empty(self):
        if self.size > 0:
            return False
        return True
    def __str__(self):
        content = ["Stack :"]
        for arr in self._arr:
            content.append(str(arr))
        return "".join(content)

if __name__ == '__main__':
    stack = Stack()
    stack.push("hi")
    stack.push("hello")
    print(stack)
    stack.pop()
    print(stack.is_empty())
    print(stack)