Is recusion the best?

Ruby
1

Hi all,

I have some codes implemented with recursion. When the loop/recursion
number is small everything looks fine to me. But the program starts
slow when the loop number is >7.I wonder if recursion is the best when
the recursion number is >7?

Thanks,

Li

#########################def table(array,word_size=1,word=’’)

hash_table=Hash.new(0)

create the keys first

array.each do |e|
if word_size==1
hash_table["#{word+e}" ]=0

else
hash_temp=table(array,word_size-1,word+e )
hash_table.merge!(hash_temp)

end
end

create the values based on keys

hash_table.each do |k,v|
hash_table[k]=k.tr(‘ACGT’,‘0123’).to_i(4)
end

return hash_table
end

######################
array=[‘A’,‘C’,‘G’,‘T’]
#array=[‘A’]
p table(array,10)

2

On Fri, Jul 24, 2009 at 11:47 AM, Li Chen[email protected] wrote:

Li

Does this do the same thing?

hash_table=Hash.new(0)
wordsize = 10

(0…4**wordsize).each do |f|
hash_table[f.to_s(4).rjust(wordsize,“0”).tr(‘0123’,‘ACGT’)] = f
end

p hash_table

Harry

3

Harry K. wrote:

Harry

Yes, they are the same. GOOD JOB!!!

Li

4

Yes, they are the same. GOOD JOB!!!

Li

Well, it is much faster, but it will start to feel very slow, too if
your word size gets much bigger.

Harry