You have to define it. The test is the one who is going to call it.

nice man

You're welcome. The pleasure is all mine ;)
Sometimes I leave descriptions to know what the solution was about. I am all the more happy when they help others :)

stauntonjr Unfortunately it was marked as a spoiler. It would probably have helped me, and I may still have been stuck, so I don't think it went too far. I had to skip in the end to see how it had been answered.

Thanks for the explanation. I skipped through to see the answers as I was perplexed, and I still didn't understand until I got here.

This is a terrible solution, brain-dead today!

Yeah, I go through phases of using functional programming styles to get better at them.

I really want to work on the reduce function a bit more but currently I've spent a lot of time training around the itertools module - lots of goodies in there :)

This is an intense solution, were you experimenting?

I agree.

I'm glad you submitted this, I was trying to remember the syntax but got stuck as I was trying to use elif!

I think it would be clearer if you described the i-th number in both cases.

fr

No, in input:

j(arr[j]) "- the number of a friend who was given a gift by friend number i", but in output:

i(arr[i]) "- the number of a friend who was given a gift by friend number i"