import ctypes

#构造函数，创建了三个属性，分为用于指定初始容量，当前大小和当前数组
def __init__ (self):'Create an empty array.'self._n = 0 #sizeself._capacity = 10self._A = self._make_array(self._capacity)

#构造函数中创建了_n属性来指定当前大小
def __len__ (self):return self._n

# _n指定当前大小
def is_empty(self):return self._n == 0

# 因为python的数组下标可以是负数，但是这边没有进行相应的实现，有兴趣的可以自行实现
def __getitem__ (self, k):if not 0 <= k < self._n:raise ValueError('invalid index') return self._A[k]

def append(self, obj):#当数组当前元素已满时，扩充容量为原来的两倍，在进行追加if self._n == self._capacity:self._resize(2 * self._capacity)self._A[self._n] = obj    self._n += 1

def _make_array(self, c):return (c * ctypes.py_object)( )def _resize(self, c):B = self._make_array(c)#扩充之后，需要将原数组中的元素copy到新数组中for k in range(self._n):B[k] = self._A[k]self._A = Bself._capacity = c

def insert(self, k, value):#当数组当前元素已满时，扩充容量为原来的两倍，在进行insertif self._n == self._capacity:self._resize(2 * self._capacity)for j in range(self._n, k, -1):self._A[j] = self._A[j-1]self._A[k] = valueself._n += 1

def pop(self,idx):if idx >= self._n:raise ValueError( 'index out of bounds' )for i in range(idx,self._n - 1):self._A[i]=self._A[i+1]self._A[self._n - 1] = Noneself._n -= 1

def remove(self, value):for k in range(self._n):if self._A[k] == value:for j in range(k, self._n - 1):self._A[j] = self._A[j+1]self._A[self._n - 1] = Noneself._n -= 1returnraise ValueError( 'value not found' )

def _print(self):for i in range(self._n):print(self._A[i], end = ' ')print()

mylist = DynamicArray()
print ('size was: ', str(len(mylist)))
mylist.append(10)
mylist.append(20)
mylist.append(30)
mylist.insert(0, 0)
mylist.insert(1, 5)
mylist.insert(3, 15)
mylist._print()
mylist.remove(20)
mylist._print()print ('size is: ', str(len(mylist)))
mylist.pop(3)
mylist._print()
print ('size is: ', str(len(mylist)))