The Final Stone The Final Stone
English UK
The mission is in Blocked Mode. Access to the solutions is blocked for a day or two (even after you share your own), until we'll have enough solutions for you to check. All users who've solved the mission will get the notifications about their opening.

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

Become Awesome

  • No Ads
  • No Limits
  • More Content
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
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