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Comment by jdp | Hacker News Reader

Even after reading the whole thing I still couldn't figure out how Jack used the rope to escape from the tower.

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Lame, I know.

In your interview at a rope pyrochronography factory, they ask you how to time 45 minutes given two ropes that each take an hour to burn.

(The ropes burn uneveningly and unequally. That is, half a rope won't necessarily burn in half an hour, and it won't necessarily be same amount of time as half of the other would take to burn - all you know is that the total time for one rope to burn is one hour.)

Okay - I'm stumped. Care to share the answer? (maybe in a day or so -- to allow others to attempt to puzzle it out?)

(Encoded with rot13.)

Yvtug ebcr 1 ng bar raq, naq ebcr 2 ng obgu raqf. Nsgre guvegl zvahgrf, ebcr 1 jvyy ohea bhg. Gura, yvtug gur bgure raq bs ebcr 2. Ebcr 2 oheaf bhg svsgrra zvahgrf yngre.

Well I think you mean: (rot13) Yvtug ebcr 1 ng bar raq, naq ebcr 2 ng obgu raqf. Nsgre guvegl zvahgrf, ebcr 2 jvyy ohea bhg. Gura, yvtug gur bgure raq bs ebcr 1. Ebcr 1 oheaf bhg svsgrra zvahgrf yngre.

But even then: (rot13) Guvf nffhzrf gung Ebcr 1 ohearq svsgl creprag va gur gvzr vg gbbx ebcr 2 gb ohea. Vs ebcr 1 bayl ohearq bar dhnegre, gura vg jvyy gnxr gjragl-gjb naq n unys zvahgrf, abg svsgrra, nsgre yvtugvat gur bgure fvqr.

(Rot 13)

Anu, vg qbrfa'g nffhzr gung. Vs ebcr 1 gnxrf 1 ubhe gb ohea, naq lbh ohea vg sbe unys na ubhe, gura vg unf unys na ubhe yrsg bs ohea gvzr. Vg qbrfa'g znggre vs gur svefg unys ubhe gbbx hc 10%, 50% be 90% bs gur ebcr yratgu, vg jvyy fgvyy svavfu oheavat va nabgure unys ubhe.

Oh yeah :-)

Vg qbrfa'g znggre ubj zhpu ohearq va 30 zvaf - ol qrsvavgvba gur erznvavat ebcr (ubjrire ybat) jvyy nyfb ohea va 30 zvaf (be 15 jvgu obgu raqf yvg).

Oh yeah :-)

Haha, when I read the question, my first thought was "he takes a knife and cuts it lengthwise. No wait... he might not have a knife. Hmmm..."

It took me a while to realize that cutting it lengthwise was the whole problem.

I thought of a different solution to the one everyone else is pitching. If you could loop the rope you might be able to get it around the tower (if the diameter of the tower is low enough, and if it's not it's a bit of an unusual tower), and then you can 'shimmie' down the tower, working around the rope as you do. I'd expect you'd have better odds doing this then splitting the rope.

If a part solution hadn't been given (tie the rope in a loop) then you might even be able to gnaw through the rope so you have it in two pieces - one to wrap around yourself as a harness so you can slide about as you work the rope down the tower. These solutions do assume that the diameter of the tower is consistent in both directions.

Although if it got thicker on the way down you might be able to loop slack into it higher up and then consume this as you descend.

Most rope has three strands twisted together. Pull these apart and tie them together. Voila - a rope that is 3 times as long (minus knots).

http://www.paddling.net/sameboat/Images/knotrope.gif The image shows what I've now learned is called "laid rope"

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