Question

如何从List<string>来源生成所有单词组合的列表？

例如，我有一个10,600多个单词的List<string>，我需要将其转换为List<List<string>>，但是，子列表只需要包含最多包含给定最大长度的组合，对于这个例子，我会说3。

我不关心单词出现在子列表中的顺序。例如，我只需要列表中的以下一项：

"laptop", "computer", "reviews" 
"laptop", "reviews", "computer"
"computer", "laptop", "reviews" 
"computer" "reviews", "laptop"
"reviews", "computer", "laptop" 
"reviews", "laptop", "computer"

是否可以根据我需要生成的大量组合来实现？

非常感谢任何帮助。

Answer 1

首先，我不确定你是否真的想要生成如此庞大的列表。如果你真的这样做，那么我建议你考虑使用iterators生成懒惰列表而不是这个巨大的列表：

static void Main()
{
    var words = new List<string> {"w1", "w2", "w3", "w4", "w5", "w6", "w7"};

    foreach (var list in Generate(words, 3))
    {
        Console.WriteLine(string.Join(", ", list));
    }
}

static IEnumerable<List<string>> Generate(List<string> words, int length, int ix = 0, int[] indexes = null)
{
    indexes = indexes ?? Enumerable.Range(0, length).ToArray();

    if (ix > 0)
        yield return indexes.Take(ix).Select(x => words[x]).ToList();

    if (ix > length)
        yield break;

    if (ix == length)
    {
        yield return indexes.Select(x => words[x]).ToList();
    }
    else
    {
        for (int jx = ix > 0 ? indexes[ix-1]+1 : 0; jx < words.Count; jx++)
        {
            indexes[ix] = jx;
            foreach (var list in Generate(words, length, ix + 1, indexes))
                yield return list;
        }
    }
}

Answer 2

希望我没有弄乱任何东西。

for(int i = 0; i < list.Count; i ++)
{
  list1 = new List<string> { list[i] };
  listcombinations.Add(list1);
  for(int j = i + 1; j < list.Count; j ++)
  {
    list1 = new List<string> { list[i], list[j] };
    listcombinations.Add(list1);
    for(int k = j + 1; k < list.Count; k ++)
    {
      list1 = new List<string> { list[i], list[j], list[k] };
      listcombinations.Add(list1);
    }
  }
}

Answer 3

我认为问题主要是检查列表中是否已存在单词组合：

你可以做些什么：

//generate a dictionary with key hashcode / value list of string
Dictionary<int, List<string>> validCombinations= new Dictionary<int, List<string>>();

//generating anyway your combinations (looping through the words)
List<string> combinationToCheck = new List<string>(){"reviews", "laptop", "computer"};

//sort the words
combinationToCheck.Sort();
string combined = String.Join("", combinationToCheck.ToArray());

//calculate a hash
int hashCode = combined.GetHashCode();

//add the combination if the same hash doesnt exist yet
if(!validCombinations.ContainsKey(hashCode))
    validCombinations.Add(hashCode, combinationToCheck);

Answer 4

private List<List<string>> GetCombinations()
{

    List<List<string>> mResult= new List<List<string>>();

    for (int i = 0; i < mList.Count; i++)
    {
        for (int k = 0; k < mList.Count; k++)
        {
            if (i == k) continue;

            List<string> tmpList = new List<string>();

            tmpList.Add(mList[i]);
            int mCount = 1;
            int j = k;
            while (true)
            {

                if (j >= mList.Count) j = 0;
                if (i != j)
                {

                    tmpList.Add(mList[j]);
                    mCount++;
                }
                j += 1;
                if (mCount >= mList.Count) break;
            }

            mResult.Add(tmpList);
        }

    }
    return mResult;
}

从List <string>单词</string>生成最多X长度的所有组合

4 个答案: