eva yang

Hi,there, I need to definea function make_tree(preorder, inorder). This function returns the Node which is the root of a binary tree with the pre-order and in-order traversals given as lists of values in the parameters. If either preorder or inorder is empty, the other must also be empty, and the …

Hi, I don't know the difference between class variables and instance variables. Can anybody give me an example? Thank you so much:)

class Toy(object): def play(self, toy): ''''Print squeak''' print 'Squeak!' class Dog(object): def __int__(self, name): '''Name a dog''' self.name = name def call(self, shout): '''Return true if shout is exactly 'Here, n!', otherwise return False''' return shout == 'Here, ' + str(self.name) + '!' def play(self, toy, n): '''Print 'Yip! ' …

Hi,there, assert pop == "berg", "Item removed from the stack was not \"berg\"." why using '...' can avoid syntax error ? Thank you :)

Hi there, Can anybody tell me what is[B] internal documentation[/B] and what is[B] external documentation[/B] based on the following example: def is_palindrome(s): '''If the str is a palindrome which is a phrase that reads the same \ forwards and backwards return True; otherwise, return False.Assume that\ there are only lowercase …

How can I use try-except to deal with an error? Thank you :)

what can i get from object.attribute? what does it do? Thank you :)

Hi all, How to write one file to the end of other file using python.