Identify Block

Identify Block

English RU

This mission uses a 4x4 grid. Each square is numbered from 1 to 16 in row-major order.
You are given 4 numbers (a set of integers). These numbers represent the positions of each square on the grid and a whole block if all the squares are adjacent.

You have to identify the kind of block. (Refer to the following image or comment of initial code for the kind of block).
The answer is an upper-case alphabet letter ('I', 'J', 'L', 'O', 'S', 'T' or 'Z'). If it’s not a block, then return None.

The block is placed anywhere on the grid and can be rotated (0, 90, 180 or 270 degrees).

Input: 4 numbers (a set of integers)

Output: the kind of block (an alphabet letter or None )


identify_block({1, 2, 3, 4}) == 'I'
identify_block({1, 2, 3, 6}) == 'T'
identify_block({1, 5, 6, 10}) == 'S'

How it is used:
For creating a tetromino puzzle.


  • len(input) == 4
  • all(1 <= num <= 16 for num in input)
  • output in ('I', 'J', 'L', 'O', 'S', 'T', 'Z', None )
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.

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