ios - 在 Swift 中推广递归/循环

Question

我正在努力在 Swift 中推广此示例代码:

let words = [ ant, apple, banana, bear, cucumber, cheese ]

... // some sorting code

var sentences = [String]()

for aWord in wordsThatStartWithA {
    bWord in wordsThatStartWithB {
        cWord in wordsThatStartWithC {
            sentences.append("\(aWord) \(bWord) \(cWord)")
        }
    }
}

// sentences -> "ant banana cucumber", "apple banana cucumber", "ant bear cucumber", ...

目标是按顺序获得包含一个 a 词、一个 b 词和一个 c 词的所有组合。但我希望能够将其推广到任何序列(即 acb、acdqp 等)

理想情况下，我想将像“acd”这样的字符串传递到返回匹配句子数组的函数中。任何帮助将不胜感激!

Answer 1

我已经想出了一个解决方案。在 Template 结构内部:

func sentencesWithWords(words: [String]) -> [String] {

    // Group vocabulary into set of template options
    let optionsSets = template.map { descriptor in
        return words.filter({ $0.matchesDescriptor(descriptor) })
    }

    // Iterate through options set
    var sentences = [String]()
    for options in optionsSets {

        // Append each option to each existing sentence
        var newSentences = [String]()
        for option in options {
            if sentences.count == 0 {
                newSentences.append(option)
            } else {
                for sentence in sentences {
                    newSentences.append("\(sentence) \(option)")
                }
            }
        }

        sentences = newSentences
    }

    return sentences
}