Very cool solution. There is an overflow for n = 31, but very clever indeed

I love the programming 101. Thank you!

There is not any hint or clue indicates that the n will greater than 3e6. I have to use my imagination to find out what time(or space) complexity is really required for this problem.

If it can't be described as confusing, I think the only word can be used here is - ridiculous.

For example, you want to calculate the sum of 1 to 100, you should not write:

var sum=0
for (var i=1;i<=100;i++) sum+=i
return sum

you only need write:

return 100*101/2

You need find out a formula ;-)

maybe you need an O(1) solution, the point of this kata is not calculate, is find a simple way to get the result.

My code can deal with game(500000) in 5s. It's not that slow for an O(n) implementation of Python.

I know may be there is a way (or many ways) to optimize. But it's not the problem.

I want know the RANGE OF DATA!

If n is 10 or less, an O(n^2) solution is fine. If n is about 10000, an O(n) solution is enough. If n is greater than 1e7, an O(1) solution is necessary.

I'm fully aware the rules of solving algorithm problems. I'm experienced.

But I hate to rewrite to code again and again, because the the f* website hides the range of data.

At the very beginning, I thought the largest n is 8!

I'm really really depressed by what the problem I'm suffering here.

and in fact, this kata did not need more calcute but need more thinking ;-)

perhaps you can paste your code here(Mark as having spoiler content) and ask someone to help you ;-)

I implemented an O(n) solution with Python, but I got TLE. I really don't know why my code runs so slow, and of course, I have no idea about the upper bound of the input n.

I'm depressed, by this problem, and by Codewars. I don't have enough information for solving the problem. I don't think it's a good idea to hide (or just ignore) the essential information for problem solving.

Codewars is not a coder friendly online judge system. Let aside the confusing output format. (gosh)

I'm confounded.

I quit.