用栈功能实现队列功能 - 《Python编程》

用栈功能实现队列功能

问题描述> 利用栈去实现队列的基本功能

问题解析> - 准备两个栈
- Stack_Date用于平常数据的压入和弹出数据
- Stack_Help用于使用栈的功能实现队列功能
  - 将Stack_Date倒置得到Stack_Help
  - 得到Stack_Help的栈顶元素为队列功能的首项元素信息: Stack_help_top
  - 删除Stack_Help的栈顶元素为队列功能的首项元素信息: Stack_help_pop

代码实现
- 封装错误python class None_Stack_Error(Exception): def __str__(self): return "There are no elements available in the stack"
  
  当范围栈顶元素时/删除栈顶元素时栈不能为空栈

list实现栈功能```python class Stack(object):

def init(self): self.__list = []

@property def Append_Stack_Number(self): return self.__list

@Append_Stack_Number.setter def Append_Stack_Number(self, Append_Stack_Number): self.__list.append(Append_Stack_Number)

@property def is_empty(self): return self.__list == []

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

@property def pop(self): if self.is_empty:
```
   raise None_Stack_Error
```
else:
```
   return self.__list.pop()
```
@property def top(self): if self.is_empty:
```
   raise None_Stack_Error
```
else:
```
   return self.__list[-1]
```
def str(self): return self.Append_Stack_Number
```
> **测试代码**
> ```python
if __name__ == '__main__':
new_Stack = Stack()
new_Stack.Append_Stack_Number = 2
new_Stack.Append_Stack_Number = 12
print(new_Stack.top)
print(new_Stack.is_empty)
#    12
#    False
```

队列功能实现```python class StackQueue: def init(self): self._Stack_Date = Stack() self.Stack_Help = Stack() self.len = 0 self.Stack_Append_Number = None

@property def StackAppend_Number(self): if self._Stack_Append_Number is not None:
```
   self._Stack_Append_Number_ = None
```
return

@property def StackDate(self): return self._Stack_Date.str()

@StackAppend_Number.setter def Stack_Append_Number(self, Stack_Append_Number): self._Stack_Append_Number = StackAppend_Number self._Append_Stack(self.Stack_Append_Number) self.Stack_Clear()

@property def StackHelp(self): return self._Stack_Help.str()

@property def Stackhelp_top(self): return self._Stack_Help.top

@property def Stackhelp_pop(self): self._len = list(self.Stack_Help.str()) try:
```
   return self._Stack_Help_.pop
```
except None_Stack_Error:
```
   return None
```
@property def isempty(self): return self._Stack_Help.is_empty

def Append_Stack(self, Stack_Append_Number): self.Stack_Date.AppendStack_Number = _Stack_Append_Number

def Stack_Clear(self): self.Stack_Help = Stack() for i in list(self.Stack_Date.str())[::-1]:
```
   self._Stack_Help_.Append_Stack_Number = i
```
```
> **测试代码**
> ```python
if __name__ == '__main__':
New_Stack_Queue = Stack_Queue()
New_Stack_Queue.Stack_Append_Number = 12
New_Stack_Queue.Stack_Append_Number = 13
New_Stack_Queue.Stack_Append_Number = 134
print(New_Stack_Queue.Stack_Help)
print(New_Stack_Queue.Stack_help_pop)
print(New_Stack_Queue.Stack_help_pop)
print(New_Stack_Queue.Stack_help_pop)
print(New_Stack_Queue.Stack_help_pop)
"""
[134, 13, 12]
12
13
134
None
"""
```