牛大叔．生活隨筆

#!/usr/bin/env ruby

require 'permutation'

str = "abcdefgh"
nums = 4  #取的個數
perm = Permutation.for("#{str}")
arr = Array.new
arr = perm.map { |p| p.project[0..(nums-1)] }.sort.uniq

arr.each do |e|
 puts e
end

puts arr.uniq.size

#!/usr/bin/env ruby

require 'permutation'

str = "12345678"
nums = 4  #取的個數
perm = Permutation.for("#{str}")
arr = Array.new
arr = perm.map { |p| p.project[0..(nums-1)].split(//).sort.join }.sort.uniq

arr.each do |e|
 puts e
end

puts arr.size