and also the one of 431 other players :-)

My solution

Because for char in s, we are iterating over each character in the string s, and for each character c, we are multiplying it by 2 (c * 2) to create a new string with the character repeated twice. The join() method is then used to concatenate all the doubled characters into a single string.

see the comments below. this solution was written in Pyrthon 2. Python 3 changed the round() function for halfway cases: it used to be half away from zero (0.5 --> 1, 1.5 --> 2), now it's half towards the nearest even integer (the so-called "banker's rounding"): (0.5 --> 0, 1.5 --> 2)

How come when I did it it was incorrect????
Which verion did you do?

Really good to know that this exist.

not efficient

Nice!

Less lines of code = better

duh

This is really quite novel. Nice!

It's not dissimilar to a 'for' loop with a list. Think of it as 'for [any item] in [what I'm telling you to look at]'.

In this case we're telling the program to look at a string, so the 'any item' is just 'any/each individual letter'. 'C' is simply a placeholder for that.

I appreciate this is checks watch 11 months late, but I hope it helps if you ever return here!

how did such a suboptimal solution get to the top?

That's brilliant! I would have never thought of that myself!