• C

# solution to towers of hanoi

i think i already know the answer but want to double check on my answer. the solution of the towers of hanoi with 7 disks requires how many disk moves? 128 disks

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Commented:
Now there's a recursive problem for ya!

Anyway, I'm coming to 127. I figure it as follows:

For a 1 disk problem: 1 disk move.

For a 2 disk problem:
Move the smallest disk to an empty
Move the bottom to another empty
Move the smallest onto the other

3 moves

For a 3 disk problem:

Move the top two to an empty:3 moves
Move the bottom to an empty
Move the two onto the bottom:3 moves

7 moves

So the number of moves for n disks looks like the number of moves for a stack one less times 2, plus one:

moves for stack of n=2*(moves for stack of n-1)+1

So we have:

1  -  1
2  -  3
3  -  7
4  -  15
5  -  31
6  -  63
7  - 127

That's almost the same you have. Are we defining the problem the same? Are we counting exactly the same thing? What do you think?
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Author Commented:
i was close..i forgot the equation of solution (2n -1)! thanks
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