KenKen Factorizor

factorize.rb

require 'prime'

def factorize x
  factors = []
  if x == 1 then return factors end
  while !Prime.prime? x
    lf = lowestFactor x
    factors.push lf
    x = x/lf
  end
  return factors.push x
end     

def lowestFactor x
  Prime.each x do |p|
    if (x/p)*p == x
      return p
    end
  end
end

def possibles arr, n=9
  return arr.push(1).push(1).combination(3)
    .map { |x| x[0]*x[1]*x[2] }
    .sort.uniq.select{ |num| num <= 9 }
end

def combos val, arr, n=4
  return arr.push(1).repeated_combination(n).sort
    .select { |x| x.reduce { |c, i| c*i } == val }
    .sort.uniq.map { |x| x.join("*") }
end

v = ARGV[0] ? ARGV[0].to_i : 2
n = ARGV[1] ? ARGV[1].to_i : 4
r = 9

f = factorize v
puts "Raw factors: " + f.join(", ")

p = possibles(f, r)
puts "Possible in 2-#{r}: " + p.join(", ")

c = combos(v, p, n)
puts "All possible combinations: " # including ones with duplicates
puts c.join("\n")

Sample output:

$ ruby factor.rb 108 4
Raw factors: 2, 2, 3, 3, 3
Possible in 2-9: 2, 3, 4, 6, 9
All possible combinations: 
2*2*3*9
2*3*3*6
2*6*9*1
3*3*3*4
3*4*9*1
3*6*6*1

3_3_3*4 is obviously not a real possible combination in KenKen. But all other possibilties should be covered