Thank you for quick response! Now I understand

Before that part of the text:

...If there are multiple solutions (and there will be), return as far as possible the result with the largest possible values:...

You need to take the solution with largest possible value for numbers with multiple possibilities

Now, back to what you asked

decompose(11) must return [1,2,4,10]. Note that there are actually two ways to decompose 11², 11² = 121 = 1 + 4 + 16 + 100 = 1² + 2² + 4² + 10² but don't return [2,6,9], since 9 is smaller than 10.

Since [1,2,4,10] has 10 which is bigger than all of the numbers in [2,6,9], you should return [1,2,4,10] instead.

what's wrong with 9 being smaller than 10 if 10 is not even part of the returned sequence?

"but don't return [2,6,9], since 9 is smaller than 10."

Not a kata issue.

Please, use issue flag/tag only when it's a problem with the kata.

Closing.

Your code is too slow for this problem. You need to optimize your approach.

Not a kata issue.

Your code being too slow is not a suggestion.

The sympy module is not among the external packages available on Codewars, you'll need to simplify the equalities manually, closing

Timed OutPassed: 67Failed: ?Exit Code: 1
Test Results:
Log
[4, 3, 2, 1, 0]
[1, 1, 0]
Fixed tests
Initial_tests
(7 of 7 Assertions)
Completed in 0.59ms
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(50 of 50 Assertions)
Medium_random_tests
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Timed OutPassed: 35Failed: ?Exit Code: 1
Test Results:
Log
[1, 2, 4, 10]
[1, 3, 5, 8, 49]
Full test suite
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4.5
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Time: 544ms Errors: 1Exit Code: 1
Show All
STDERR:
Traceback (most recent call last):
File "/workspace/default/tests.py", line 1, in
from solution import simplify
File "/workspace/default/solution.py", line 3, in
from sympy import symbols, Eq, solve
ModuleNotFoundError: No module named 'sympy'

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