Under every kata i do is always a single clever person with single line solution to a problem :P I really admire you guys :)

Kudos to the people that actually thought about the mathematics behind the question. I feel stupid now...

In c++ 0 is for false and 1 is for true. Use boolalpha for literal use of true and false.

Use spoiler flag next time, please.

can someone explain to me what happens in the loop ,thank you in andvance

do you know if such function exists in c++?

There is several ways for this kind of work. But it depends on the language you are using. As an example, in c# there is a string function called Insert(). Using that function you can easilly do this task. There is some equivallent functions in most of the language. You should consult the respected documentation.

how do u insert a number to a string ,i mean to its full length ,like n=89 str[0]=8 and str[1]=9.
thank you in advance

the output iis always 0

What is your problem?

This is weird, when I display my answer(which is an array) in the console it is correct but when I try return the answer(which is an array) it runs my code multiple times which causes me to get the answer wrong. Why is it doing that? scratching my head

Look at the function return type, and then at the value you're trying to return.