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我想定义一个计数函数来计算树中满足谓词的每个数字。如何计算数字符合谓词的数字树?
#given function:
class TN:
def __init__(self,value,left=None,right=None):
self.value = value
self.left = left
self.right = right
def add(atree,value):
if atree == None:
return TN(value)
if value < atree.value:
atree.left = add(atree.left,value)
return atree
elif value > atree.value:
atree.right = add(atree.right,value)
return atree
else:
return atree # already in tree
def add_all(atree,values):
for v in values:
atree = add(atree,v)
return atree
def is_prime (x):
assert type(x) is int and x >= 0, 'predicate.is_prime x is not a positive int: '+str(x)
if x <= 2:
return x == 2
for i in range(2,x):
if x % i == 0:
return False
return True
add_all函数接受一个列表并返回一棵树。 如果int参数为素数,则is_prime函数返回True。
#function I am trying to define (a recursive function: count):
def count(t,p):
if t==None:
return 0
else:
return 1+count((t.left if p(t.left.value) else t.right),p)
例如,
import random
values = [i for i in range(1,200)]
random.shuffle(values
) ###调用计数功能如下应该给我: 计数(add_all(无,值),is_prime)# - > 46
我计数功能给我:
AttributeError: 'NoneType' object has no attribute 'value'
我是新来使用TR ee,我认为我有问题来定义递归计数函数。
非常感谢! – Saoish 2014-11-23 02:06:16
再次感谢细节,现在我明白了。 – Saoish 2014-11-23 02:12:06