从多个(n)列表中生成所有组合 [英] Generate all Combinations from Multiple (n) Lists

问题描述

我已经完全弄清了我的问题，因为我已经找到了问它的最简单方法.到目前为止，感谢评论者让我思考了根本问题.

I am completely redoing my questions as I have figured out the simplest way of asking it. Thanks to the commenters so far that got me thinking about the root problem.

public List<string> GetAllPossibleCombos(List<List<string>> strings)
{
    List<string> PossibleCombos = new List<string>();

    //????
    {
        string combo = string.Empty;
        // ????
        {
            combo += ????
        }
        PossibleCombos.Add(combo);
    }

    return PossibleCombos;
}

我需要弄清楚如何递归地遍历每个List<string>并将每个列表中的1个字符串组合成一个组合string.不必担心格式化字符串，因为实时"代码使用自定义对象代替.另外，请随意假设每个列表将至少包含1个字符串，并且不存在空值.

I need to figure out how to recursively go through each List<string> and combine 1 string from each list into a combo string. Don't worry too much about formatting the string as the "live" code uses a custom object instead. Also, feel free to assume that every list will contain at least 1 string and that there are no null values.

推荐答案

希望这会有所帮助.

class NListBuilder

{
    Dictionary<int, List<string>> tags = new Dictionary<int, List<string>>();

    public NListBuilder()
    {
        tags.Add(1, new List<string>() { "A", "B", "C" });
        tags.Add(2, new List<string>() { "+", "-", "*" });
        tags.Add(3, new List<string>() { "1", "2", "3" });
    }

    public List<string> AllCombos
    {
        get
        {
            return GetCombos(tags);
        }
    }

    List<string> GetCombos(IEnumerable<KeyValuePair<int, List<string>>> remainingTags)
    {
        if (remainingTags.Count() == 1)
        {
            return remainingTags.First().Value;
        }
        else
        {
            var current = remainingTags.First();
            List<string> outputs = new List<string>();
            List<string> combos = GetCombos(remainingTags.Where(tag => tag.Key != current.Key));

            foreach (var tagPart in current.Value)
            {
                foreach (var combo in combos)
                {
                    outputs.Add(tagPart + combo);
                }
            }

            return outputs;
        }


    }
}

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