It really doesn't matter what level you're at — working with prime numbers is always both fun and challenging.
Thanks for the sexy challenge! 🙌🔢💖

Shit! I see my mistake, repeated once means each letter appears twice. The kata is okay

The instruction is misleading - It states: Given a string, you have to return a string in which each character (case-sensitive) is repeated once.
"return a string in which each character (case-sensitive) is repeated once" should be changed to "return a string in which each character (case-sensitive) is repeated twice". That would help.

Not a kata issue. Your code is wrong, you are removing duplicates in the string whilst the question asks to double each character in the string.

Also, you are misunderstanding the logs

'String' should equal 'SSttrriinngg'

Meaning that

actual (what your code returned) should equal Expected correct result from the tests

The tests are broken, in Python - The expected result and actual result are reversed

Forked and approved

LGTM, approved

Take a look at the comments in solution setup: you are not meant to allocate any memory, but you are expected to use the doubled buffer and write your answer into it, and then return the doubled.

Your solution is almost correct, you just should write to doubled without malloc-ing it.

A great little exercise.

my bad. thanks for your time. I am n3wb.

You are using the wrong function name. Should be double_char whilst yours is repeat_each_letter

I am getting this error

Traceback (most recent call last):
File "/workspace/default/tests.py", line 2, in
from solution import double_char
ImportError: cannot import name 'double_char' from 'solution' (/workspace/default/solution.py)

C++ Translation

Thank you so much hobovsky and Chrono79, I was trying to print the output causing the test to fail, it passed now after making the required changes