arrays - Permutations in Ruby - unsure how to handle -

i trying output array of 10-element arrays containing permutations of 1 , 2, e.g.:

 [[1,1,1,1,1,1,1,1,1,1],  [1,1,1,1,1,1,1,1,1,2],  [1,2,1,2,1,2,1,2,1,2],  ...etc...  [2,2,2,2,2,2,2,2,2,2]] 

i have done smaller arrays, (10):

 = [1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2]  = a.permutation(10).to_a  print a.uniq 

...this apparently big calculation- after hour running, hadn't completed , ruby process sitting on 12gb of memory. there way come @ this?

first, check size of permutation

a.permutation(10).size  => 670442572800 

it's huge. can instead use array#repeated_permutations on smaller array. check here:

b = [1, 2] # unique elements b.repeated_permutation(10) # returns enumerable b.repeated_permutation(10).to_a # creates array of permutations 

those permutations unique (which u can check printing size , without array#uniq )