如何在 ruby​​ 中组合/排列? [英] How to combination/permutation in ruby?

问题描述

我有一个熟悉的问题，看起来像是数学世界的排列/组合.

I've this familiar question that looks like permutation/combination of the Math world.

如何通过 ruby​​ 实现以下目标?

How can I achieve the following via ruby?

badges = "1-2-3"

badge_cascade = []
badges.split("-").each do |b|
  badge_cascade << b
end

Gives: => ["1", "2", "3"]

But I want it to be is:

=> ["1", "2", "3", 
  "1-2", "2-3", "3-1", "2-1", "3-2", "1-3", 
  "1-2-3", "2-3-1", "3-1-2"]

推荐答案

函数式方法:

bs = "1-2-3".split("-")
strings = 1.upto(bs.size).flat_map do |n| 
  bs.permutation(n).map { |vs| vs.join("-") } 
end
#=> ["1", "2", "3", "1-2", "1-3", "2-1", "2-3", "3-1", "3-2", "1-2-3", "1-3-2", "2-1-3", "2-3-1", "3-1-2", "3-2-1"]

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