在 Ruby 中从多维数组创建排列 [英] Creating permutations from a multi-dimensional array in Ruby

问题描述

我在 Ruby 中有以下多维数组:

I have the following multi-dimensional array in Ruby:

[[1,2], [3], [4,5,6]]

我需要有以下输出:

[[1,3,4], [1,3,5], [1,3,6], [2,3,4], [2,3,5], [2,3,6]]

我尝试过创建递归函数，但运气不佳.

I have tried creating a recursive function, but I'm not having much luck.

是否有任何 Ruby 函数可以帮助解决此问题?或者是递归执行的唯一选择?

Are there any Ruby functions that would help with this? Or is the only option to do it recursively?

谢谢

推荐答案

是的，Array#product 就是这样做的(笛卡尔积):

a = [[1,2], [3], [4,5,6]]
head, *rest = a # head = [1,2], rest = [[3], [4,5,6]]
head.product(*rest)
#=> [[1, 3, 4], [1, 3, 5], [1, 3, 6], [2, 3, 4], [2, 3, 5], [2, 3, 6]] 

另一种变体:

a.inject(&:product).map(&:flatten)
#=> [[1, 3, 4], [1, 3, 5], [1, 3, 6], [2, 3, 4], [2, 3, 5], [2, 3, 6]] 

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