# Reverse Engineer

Challenging
English

You are standing next to a math machine which takes two numerical inputs x and y , and has a single numerical output. It is known that the machine evaluates an expression using x , y , the operators + – * / and brackets . You should recover the expression by using the machine and the inputs of your choice over several turns. x , y and the result you receive are integers. The machine uses real division( / ) in the expression. When dividing by zero, the result will evaluate to "ZeroDivisionError" .

Equivalent expressions will be accepted by the grader. For this the machine evaluates your expression and the hidden expression several times using random values.

In each step your function gets a list with data from the past steps. Each element is a list of three numbers -- x (int), y (int) and output (a fraction as a list or the string "ZeroDivisionError"). The output is represented as a list with two integers - numerator and denominator.

The function should return a list with three elements -- your guess as an expression string, x and y , as integers.

Input: A list with data from the past steps.

Output: A list with three elements -- your guess as an expression string, x (int) and y (int).

Example:

checkio([])  # hidden expression "x+y"
checkio([[2, 2, [4, 1]]]) # ["x*y", 3, 3]
checkio([[2, 2, [4, 1]], [3, 3, [6, 1]]])  # ["x+y", 5, 5]

How it is used: The concepts used in this task can help you to understand someone else’s code and add new techniques to your own repertoire. In addition to this, reverse engineering comes in handy in cryptology where it can be used to decrypt coded information.

Precondition: The hidden expression is correct. It does not evaluate at ZeroDivisionError always.

26
Settings
Code:
Other:
Invalid hot key. Each hot key should be unique and valid
Hot keys:
•  to Run Code: to Check Solution: to Stop:
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

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.

Pair Programming (Beta-version)

Welcome to Pair Programming! Engage in real-time collaboration on coding projects by starting a session and sharing the provided unique URL with friends or colleagues. This feature is perfect for joint project development, debugging, or learning new skills together. Simply click 'Start Session' to begin your collaborative coding journey!

Waiting for Pair Programming to start...

You are trying to join a pair programming session that has not started yet.

Please wait for the session creator to join.

Waiting for Pair Programming to reconnect...

It looks like the creator of the pair programming session closed the editor window.

It might happen accidentally, so that you can wait for reconnection.