[python]CategoryTree的设计与实现

CatagoryTree的设计与实现

题目要求

＃输入
if __name__== '__main__':
c = CatagoryTree()
c.add_catagory('A',None)
c.add_catagory('B','A')
c.add_catagory('C','A')
print ','.join(c .get_children('A'))

输出：B,C或者C,B

设计

+--------------+
|    object    |
+--------------+
.
/_\
|                [ object ]
|                    .
|                   /_\
|                    |
|                    |
+--------------+       +----------+
| CatagoryTree |       |   Node   |
|--------------|       |----------|
| tree         |       | base     |
|--------------|       | parent   |
| __init__     |       | children |
| add_catagory |       |----------|
| get_children |       | __init__ |
+--------------+       +----------+

实现

#-*- coding:utf-8 -*-
class CatagoryTree(object):
def __init__(self):
self.tree = []
class Node(object):
def __init__(self,base,parent=(None),children=[]):#parent只能有一个，应该是Tuple类型。而children长度是可变的，应该是List类型
self.base= base
self.parent = parent
self.children = children
def add_catagory(self,a,b):
#当b为None时，将a作为tree的根节点
if b is None:
a = self.Node(a)
self.tree.append(a)
else:
#不然的话，就遍历tree
flag = False
for _ in self.tree:
#当找到b时，将a插入b的孩子节点中
if _.base ==b:
a = self.Node(a)
_.children.append(a)
a.parent = _.base
flag = True
#当找不到b时，抛异常
if not flag:
print 'Parent Node %s is not exist!'%a

def get_children(self,a):
#遍历tree找a
#if 找到:
#return a.children
#else:
#return 'a is not exist.'
it = iter(self.tree)
while(True):
try:
_ = next(it)
if _.base==a:
return [__.base for __ in _.children]
except StopIteration:
print 'Base Node %s !exist'%a
break

if __name__== '__main__':
c = CatagoryTree()
c.add_catagory('A',None)
c.add_catagory('B','A')
c.add_catagory('C','A')
print ','.join(c .get_children('A'))
c.get_children('D')
c.add_catagory('C','D')