红宝石 - 如何从一个字符串数组的字母顺序可能的组合？

问题描述

我有一个字符串数组：

  [ABC，GHI]
 

广告我希望所有的字母的组合，作为读取由左到右，即

  [公司，啊，人工智能，BG，BH，商业智能，CG，CH，CI]
 

而不是

 GA，GB，HA，等等。
 

同样，

  [ABC，DEF，GHI]
 

应该产生

  [ADG，ADH，阿迪，AEG，爱德华，AEI，AFG，AFH，AFI， BDG，BDH，
BDI，乞，BEH，被，BFG，BFH，BFI，CDG，鼎晖，CDI，CEG
CEH，CEI，CFG，CFHCFI]
 

而不是

 DAG，GAD或建筑面积
 

解决方案

这是你所需要的：

  A = [ABC，DEF，GHI]
a.map（安培;：字符）。降低（安培;：产品）.MAP（安培;：加入）
 

顺便说一句，你在你的例子输出做了一些错误，但绝不应先从E或根据您的规范中的F均被。所以我想，而不是ECH，ECI，FCG，FCH，FCI你的意思CEH， CEI，CFG，CFH，CFI。

编辑：

字符返回一个枚举，而不是一个数组，并用Ruby 2.0之前那些版本没有产品方法。因此，在这些版本中，只需要使用 to_a 是这样的：

  a.map（安培;：字符）.MAP（安培;：to_a）。降低（安培;：产品）.MAP（安培;：加入）
 

I have an array of strings:

["ABC", "GHI"]

ad I want all the 'letter' combinations, as reads from left to right, i.e.

["AG", "AH", "AI", "BG", "BH", "BI", "CG", "CH", "CI"]

but not

"GA", "GB", "HA", etc.

Similarly,

["ABC", "DEF", "GHI"]

should generate

["ADG", "ADH", "ADI", "AEG", "AEH", "AEI", "AFG", "AFH", "AFI", "BDG", "BDH", 
"BDI", "BEG", "BEH", "BEI", "BFG", "BFH", "BFI", "CDG", "CDH", "CDI", "CEG", 
"CEH", "CEI", "CFG", "CFH" "CFI"]

but not

"DAG", "GAD" or "GFA"

解决方案

This is what you need:

a = ["ABC","DEF", "GHI"]
a.map(&:chars).reduce(&:product).map(&:join)

By the way, you made some errors in your example output, there should never be strings starting with an E or an F according to your specification. So I suppose instead of "ECH", "ECI", "FCG", "FCH", "FCI" you meant "CEH", "CEI", "CFG", "CFH", "CFI".

Edit:

chars returns an Enumerator, not an array, and in Ruby versions before 2.0 those don't have a product method. So in those versions, just use a to_a like this:

a.map(&:chars).map(&:to_a).reduce(&:product).map(&:join)

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