## Wednesday, April 28, 2010

### The Camels

Four tasmanian camels traveling on a very narrow ledge encounter four tasmanian camels coming the other way.
Tasmanian camels never go backwards, especially when on a precarious ledge. The camels will climb over each other, but only if there is a camel sized space on the other side.
The camels didn't see each other until there was only exactly one camel's width between the two groups.
How can all camels pass, allowing both groups to go on their way, without any camel reversing?

Hint: to help visualize, use paper clips or coins.

Solution:
Let the camels on the left be 1> 2> 3> and 4>.  Let the camels on the right be <A <B <C <D.  Arrow indicates direction the camel is facing.  One possible solution (although I think the only other solution is symmetrical to this one - let me know if you find others):
1> 2> 3> 4> ..... <A <B <C <D
1> 2> 3> 4> <A ..... <B <C <D
1> 2> 3> ..... <A 4> <B <C <D
1> 2> ..... 3> <A 4> <B <C <D
1> 2> <A 3> ..... 4> <B <C <D
1> 2> <A 3> <B 4> ..... <C <D
1> 2> <A 3> <B 4> <C ..... <D
1> ..... <A 2> <B 3> <C 4> <D
..... 1> <A 2> <B 3> <C 4> <D
..... .... <A 1> <B 2> <C 3> <D 4>
..... .... <A .... <B 1> <C 2> <D 3> 4>
..... .... <A .... <B .... <C 1> <D 2> 3> 4>
..... .... <A .... <B .... <C .... <D 1> 2> 3> 4>
..... <A .... <B .... <C .... <D .... 1> 2> 3> 4>
<A <B <C <D .... 1> 2> 3> 4>

1. This comment has been removed by the author.

2. Both animal groups even

3. We'll call the camels on the left A B C D and the camels on the right 1 2 3 4. The order is read left to right for both camel groups.

D, 1 climbs, 2, D climbs, C climbs, B. All number camels can now climb to the other side.

Ignore the first two. Typos abound.

4. i did it! hard to describe, you just gotta figure it out w/ trial & error, no?

5. Can't the camels just push each other off? Survival of the fittest right?

6. I can do it in 6 moves