June 2018 Update

Task/Factors-of-an-integer/Ruby/factors-of-an-integer-3.rb

@@ -0,0 +1,12 @@
+require 'prime'
+
+def factors m
+  return [1] if 1==m
+  primes, powers = Prime.prime_division(m).transpose
+  ranges = powers.map{|n| (0..n).to_a}
+  ranges[0].product( *ranges[1..-1] ).
+  map{|es| primes.zip(es).map{|p,e| p**e}.reduce :*}.
+  sort
+end
+
+[1, 7, 45, 100].each{|n| p factors n}