English FR IT JA RU

For the mission "How to find friends" , it’s nice to have access to a specially made data structure. In this mission we will realize a data structure which we will use to store and work with a friend network.

The class "Friends" should contains names and the connections between them. Names are represented as strings and are case sensitive. Connections are undirected, so if "sophia" is connected with "nikola", then it's also correct in reverse.

class Friends (connections)

Returns a new Friends instance. "connections" is an iterable of sets with two elements in each. Each connection contains two names as strings. Connections can be repeated in the initial data, but inside it's stored once. Each connection has only two states - existing or not.

>>> Friends(({"a", "b"}, {"b", "c"}, {"c", "a"}, {"a", "c"}))
>>> Friends([{"1", "2"}, {"3", "1"}])

add ...

>>> f = Friends([{"1", "2"}, {"3", "1"}])
>>> f.add({"1", "3"})
>>> f.add({"4", "5"})

remove (connection)

Remove a connection from the instance. "connection" is a set of two names (strings). Returns True if this connection exists. Returns False if this connection is not in the instance.

>>> f = Friends([{"1", "2"}, {"3", "1"}])
>>> f.remove({"1", "3"})
>>> f.remove({"4", "5"})

names ()

Returns a set of names. The set contains only names which are connected with somebody.

>>> f = Friends(({"a", "b"}, {"b", "c"}, {"c", "d"}))
>>> f.names()
{"a", "b", "c", "d"}
>>> f.remove({"d", "c"})
>>> f.names()
{"a", "b", "c"}

connected (name)

Returns a set of names which is connected with the given "name" . If "name" does not exist in the instance, then return an empty set.

>>> f = Friends(({"a", "b"}, {"b", "c"}, {"c", "a"}))
>>> f.connected("a")
{"b", "c"}
>>> f.connected("d")
>>> f.remove({"c", "a"})
>>> f.connected("c")
>>> f.remove({"c", "b"})
>>> f.connected("c")

In this mission all data will be correct and you don't need to implement value checking.

Input: Statements and expression with the Friends class.

Output: The behaviour as described.

How it is used: Here you will implement a class with mutable states. This is not a simple structure with a couple of functions, but object representation with more complex structure.

Precondition: All data is correct.

You should be an authorized user in order to see the full description and start solving this mission.
CheckiO Extensions

CheckiO Extensions allow you to use local files to solve missions. More info in a blog post.

In order to install CheckiO client you'll need installed Python (version at least 3.8)

Install CheckiO Client first:

pip3 install checkio_client

Configure your tool

checkio --domain=py config --key=

Sync solutions into your local folder

checkio sync

(in beta testing) Launch local server so your browser can use it and sync solution between local file end extension on the fly. (doesn't work for safari)

checkio serv -d

Alternatevly, you can install Chrome extension or FF addon

checkio install-plugin
checkio install-plugin --ff
checkio install-plugin --chromium

Read more here about other functionality that the checkio client provides. Feel free to submit an issue in case of any difficulties.

<< <
> >>
exec show

Whats Next?

Free accounts will see Best CheckiO solutions with some delay.
Best Solutions will be opened in a moment
Become Awesome and Don't wait
The next stage is ""
Will be activated in
View More Solutions Random Review Solutions Go to the next mission