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Old 06-25-2010, 09:44 AM   #13
omk3
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Quote:
Originally Posted by pdurrant View Post
Yes, that works — a correct answer. Well done!

Spoiler:
You've got him out of the desert in 12 days. There is at least one faster solution. Can you find it?
But:

Spoiler:
The way I see it, the number of days must always be even, to account for round trips. It would take him 6 days to cross the desert if he could carry all the water, 8 days if he needed to walk back one day for refresments, 10 days if he needed to walk two days back for refreshments, or walk one day back for refreshments twice. Whatever I try I need him to go back 3 times minimum.

I can't see a way around getting back on the first day. If he walks for 2 days, then he needs to go back, so will have to consume the whole 4 day supply of water. No good. So the first round-trip must be done.

Walk 1 day, leave 2 day's water, walk back.

From then on I tried a multitude of options, but none amounts to less than 12 days.

And I need to get some work done, too! Arghh...
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