Algorithm help!!!

[BlueJay924]

is there an algorithm for 2^n-1? i'm trying to get all the possibilities from an array and store each combination into an arraylist. is there a name for this algorithm? help would be appreciated

[Heiko]

You don't need a complex algorithm to calculate (2^n)-1.

 

Having said that, I conclude that I didn't fully understand your problem :)

 

You have an array of length n.

Each array element can either be 0 or 1 ?

And you want to transform this into another array with 2^n elements, each element containing the unique (0/1) combination ?

 

 

I don't know any named algorithm for that.

Basically it's a bit-array to word conversion.

So you could just fill your second array with all numbers from zero to n and interpret them as bitarrays.

[BlueJay924]

your bit about it being 1/0s is right but let me go a litte more into what i'm trying to do

 

supp i have my array

 

a : 1, 2, 3, 4

 

i want to be able to get all the possible combinations (the array size may vary)

 

result would be

1

12

13

14

123

124

134

1234

2

23

24

234

3

34

4

 

but is there a an algorithm that will give me this combination because if there is my brain just does not want to see it.

[Jay1b]

You could have 4 loops, each embedded in another, using a if statement to only write them, if they are not the same.

[Heiko]

No. That would limit the array size to 4.

 

Are you familiar with recursive algorithms ?

 

' P S E U D O C O D E
'
Sub Pick (ByVal pool as array, byval pickstring as string) 

If pool.length = 0 then
 Debug.writeline (pickstring)
else
for each elem in pool
  Pick (New array (old pool minus elem), pickstring & elem)
next elem
end if
next

[Jay1b]

He asked for 4 loops :)

 

Ok, have a loop held in a class, then within that loop have it call the class for x amount of times. Not at all complex.