Question

I am trying to figure how how to find all the combinations given the following information:

I start with a JSON dataset:

var choices = { 1: {'Q': 100, 'R': 150, 'W' : 250, 'T', 30},
                2: {'Q': 90, 'R': 130, 'W' : 225, 'T', 28},
                3: {'Q': 80, 'R': 110, 'W' : 210, 'T', 25},
                4: {'Q': 70, 'R': 90, 'W' : 180, 'T', 22},
                5: {'Q': 60, 'R': 70, 'W' : 150, 'T', 18},
                6: {'Q': 50, 'R': 50, 'W' : 110, 'T', 15},
                7: {'Q': 40, 'R': 30, 'W' : 80, 'T', 11},
                8: {'Q': 30, 'R': 25, 'W' : 50, 'T', 8},
                9: {'Q': 20, 'R': 10, 'W' : 25, 'T', 5},
                10: {'Q': 10, 'R': 5, 'W' : 15, 'T', 3}
              };

What I’m trying to figure out is how I can take this dataset, and generate all possible combinations when selecting either the ‘Q’, ‘R’, ‘W’, or ‘T’ element for each row.

So I hope my end result will be something like this

var allChoices = { 0: {1: {'Q': 100},
                       2: {'R': 130},
                       3: {'W' : 210},
                       4: {'W' : 180},
                       5: {'T', 18},
                       6: {'R': 50,},
                       7: {'Q': 40,},
                       8: {'T', 8},
                       9: {'R': 10},
                      10: {'W' : 15},
                     },
                 1: {...},
                 ...
                 1048576: {...}

              };

I used JSON because I think it is the easiest to visualize but does anyone know how I could go about accomplishing this in c#?

Let me know if this not clear enough I’m having a hard time figuring out how exactly to ask this question.

Answer 1

Here’s How to do it using depth first Recursion. Takes about 3 seconds to run on my machine. Also this will work for an arbitrary sized pairing by changing the PAIRCOUNT to say 5 if you had 5 columns instead of 4 and just .add the additional Pairs as appropriate.

    void Main()
    {
        var OriginValues = new List<KeyValuePair<char, int>>();
        OriginValues.Add(new KeyValuePair<char, int>('Q', 100));
        OriginValues.Add(new KeyValuePair<char, int>('R', 150));
        OriginValues.Add(new KeyValuePair<char, int>('W', 250));
        OriginValues.Add(new KeyValuePair<char, int>('T', 30));

        OriginValues.Add(new KeyValuePair<char, int>('Q', 90));
        OriginValues.Add(new KeyValuePair<char, int>('R', 130));
        OriginValues.Add(new KeyValuePair<char, int>('W', 225));
        OriginValues.Add(new KeyValuePair<char, int>('T', 28));

        OriginValues.Add(new KeyValuePair<char, int>('Q', 80));
        OriginValues.Add(new KeyValuePair<char, int>('R', 110));
        OriginValues.Add(new KeyValuePair<char, int>('W', 210));
        OriginValues.Add(new KeyValuePair<char, int>('T', 25));

        ///... and the other 7

        var AllPermutation = new List<List<KeyValuePair<char, int>>>();
        Recurse(OriginValues, ref AllPermutation);

        //all results will be in AllPermutation now

    }

    const int PAIRCOUNT = 4;
    void Recurse(List<KeyValuePair<char, int>> OriginValues, ref List<List<KeyValuePair<char, int>>> result, List<KeyValuePair<char, int>> itemset = null)
    {
        itemset = itemset ?? new List<KeyValuePair<char, int>>();
        var temp = new List<KeyValuePair<char, int>>(itemset);
        if (itemset.Count == OriginValues.Count / PAIRCOUNT)
        {
            result.Add(temp);
            return;
        }
        for (int x = 0; x < PAIRCOUNT; x++)
        {
            temp.Add(OriginValues[itemset.Count * PAIRCOUNT + x]);
            Recurse(OriginValues, ref result,  temp);
            temp = new List<KeyValuePair<char, int>>(itemset);
        }

    }