The Kayaker’s Conundrum: An Exercise in Computational Thinking

20160928_181301Here’s a middle class problem that requires some computational thinking.

There are two of us, and we each have a single person kayak. We want to go for a paddle down the river. We can attach our kayaks to the top of our car, so we can drive them to the start. Trouble is, we can only paddle downstream. We can’t turn round and paddle back to the start: the current is too strong. We can attach bikes to the back of our car, so we could use them somehow. We have locks for our bikes, but not our kayaks, and don’t want to leave anything alone, unless its locked. We are not prepared to walk at any time, apart from walking the kayaks into and out of the river.

How can we best utilise our resources so we can go for a paddle and still get everything home again without having to walk anywhere?

Hint: There are a couple of algorithms you can use to solve the conundrum. But which is best? Which will involve the least amount of driving? Does it depend on where you live: close to the start or close to the finish? What if you live half way between the start and finish?

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2 thoughts on “The Kayaker’s Conundrum: An Exercise in Computational Thinking

  1. Jim Muir

    Would this work?
    Drive to the end and lock the bikes up
    Drive to the start with Kayaks
    Lock the car and paddle down the river
    At the end of the paddle person 1 stays with the two kayaks and one bike
    Person 2 cycles back to the start to collect the car
    Car is driven back to the end to collect person 1, two kayaks and the remaining bike

    Reply
    1. computing-made-simple Post author

      Brilliant. Yes that would work, but you actually only need one bike. We probably should have said that in the description of the conundrum.

      There is another way of doing it, and the best algorithm in terms of distance driven depends on whether you live near the start or the finish. If you live mid way between the start and the finish it makes no difference which of the two algorithms you choose. At least that’s what we think so far!

      Reply

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