On Tue, Nov 22, 2011 at 4:32 AM, Steven D'Aprano <st...@pearwood.info>wrote:
> John wrote: > >> >> Hi all, >> >> I have wriiten the following code: >> [Segment] >> >> def survivor(names, step): >>>>> >>>> index = step - 1 >> next = names >> while len(next)> 1: >> next.remove (next[index]) >> > > > What is the intention of this function? The name given doesn't mean > anything to me. The parameters "names" and "step" don't seem meaningful. > I guess he is trying the Josephus problem. I am guessing from the name! If so, you have to remember that when you delete an item you change the positions of subsequent items. For example, in a 11-element list, say A, if you want to delete every third, the index numbers you *should* delete are 2, 5, 8. But if you delete A[2], then you will delete the original A[6] and then the original A[10]. So you have to think in terms of 'marking' for deletion and later deleting or deleting from the other end. A more interesting possibility is to replicate the original list and append it to itself and "delete" all occurrences. About 25 years back thats what I did in BASIC and won an honorable mention in a coding contest in a magazine :-) I replaced the cell contents with a space and in subsequent rounds counted non-space items. The first prize was won by a circular(linked-)list in Pascal, with the same repace by Space idea HTH Asokan
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