OP solved it, closing

Your code doesn't work when there are negative numbers in array1. Your variable nuevo becomes unordered.

Check out the troublehooting link from my previous post.

Without formatting, your code is unreadable :/

Try to format it like it's shown here: https://docs.codewars.com/references/markdown/#code-block

You could also check which input causes the failure, see this post: https://docs.codewars.com/training/troubleshooting/#print-input

OP solved the kata (while still returning a stack array from the function, remarkably)

OP solved the kata

OP solved the kata + problem not reproducible with his solution

you return the address of a local (stack-allocated) array, as the warning tells you:

warning: address of stack memory associated with local variable 'result' returned [-Wreturn-stack-address]

ty, the print was the problem

i added instructions and a call to free() in this fork

Please see this paragraph.