The Final Stone

The Final Stone


You have a list of stones with different weights. The result of hitting two stones will be a new stone with a weight difference between the two stones.


Your goal is to find the weight of the final stone. If no stones left, the result is 0.

The algorith is very simple:

  • get the two biggest stones in the batch
  • hit and get the resulting stone
  • put the resulting stone back in the batch.

For the Speedy category, you can think about your solution for a million stones

Input: List of stones as list of ints

Output: Int.


assert final_stone([3, 5, 1, 1, 9]) == 1
assert final_stone([1, 2, 3]) == 0
assert final_stone([1, 2, 3, 4]) == 0
assert final_stone([1, 2, 3, 4, 5]) == 1

Precondition: only positive, non-zero values. The list of stones can be empty

Invalid hot key. Each hot key should be unique and valid
Hot keys:
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.

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!

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Please wait for the session creator to join.

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

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