Welcome to the Lounge

Griff wrote:

it's kinda using QuickSort to match 'em up.

using System;
using System.Collections.Generic;

namespace ConsoleApp3
{
    class Program
    {
        static void Main(string[] args)
        {
            // prep the data
            Parts nuts = new Parts();
            Parts bolts = new Parts(nuts);

            nuts.Sort();
            bolts.Sort();

            foreach(Part nut in nuts)
            {
                Part bolt = bolts[nuts.IndexOf(nut)];
                Console.WriteLine("Pair: [{0}] - [{1}]", nut, bolt);
            }
            Console.ReadKey();
        }
    }

    public enum HardwareType { BOLT=0, NUT}

    /// The "part" (all parts have a hardware type, a diameter and pitch)
    public class Part : IComparable<Part>
    {
        public HardwareType Hardware { get; set; }
        public int ItemID { get; set; }
        public int Diameter { get; set; }
        public int Pitch { get; set; }
        public Part(int itemID, int diameter, int pitch, HardwareType hardware)
        {
            this.ItemID   = itemID;
            this.Diameter = diameter;
            this.Pitch    = pitch;
            this.Hardware = hardware;
        }

        public int CompareTo(Part p)
        {
            return this.Diameter.CompareTo(p.Diameter);
        }

        // make it more convenient to look at in the debugger
        public override string ToString()
        {
            return string.Format("{0}, ID={1}, D={2}, P={3}", this.Hardware.ToString(), this.ItemID, this.Diameter, this.Pitch);
        }
    }

    public class Parts : List<Part>
    {
        // This constructor builds a collection of nuts
        public Parts(bool populate=true)
        {
            if (populate)
            {
                // create a list of "part"s with randomly selected combinations of diameter and pitch
                List<int> diameters = new List<int>(){  1, 2, 3, 4, 5, 6, 7, 8, 9,10 };
                List<int> pitches   = new List<int>(){ 11,12,13,14,15,16,17,18,19,20 };
                Random    diaRandom = new Random(1);
                Random    pitRandom = new Random(3);
                int diaIndex;
                int pitIndex;
                int id = 0;
                do
                {
                    diaIndex = diaRandom.Next(0, diameters.Count-1);
                    pitIndex = pitRandom.Next(0, pitches.Count-1);
                    this.Add(new Part(id, diameters[diaIndex], pitches[pitIndex], HardwareType.NUT));
                    diameters.RemoveAt(diaIndex);
                    pitches.RemoveAt(pitIndex);
                    id++;
                } while (diameters.Count > 1);
                this.Add(new Part(id, diameters[0], pitches[0], HardwareType.NUT));
                diameters.RemoveAt(0);
                pitches.RemoveAt(0);
            }
        }

        // this constructor build acollection of bolts based on the nuts collection provided.
        public Parts(Parts parts)
        {
            // we can't randoly select dia/pitch again, and we can't randmly select nuts and 
            // delete them from the list without destroying the original list, so we clone 
            // the colllection of nuts
            Parts cloned = new Parts(false);
            cloned.AddRange(new List<Part>(parts));

            // and now we can rendomly select a nut from the cloned collection
            Random random = new Random();
            int index;
            int id = 0;
            do
            {
                index = random.Next(0,cloned.Count-1);
                this.Add(new Part(id, cloned[index].Diameter, cloned[index].Pitch, HardwareType.BOLT));
                cloned.RemoveAt(index);
                id++;
            } while (cloned.Count > 1);
            this.Add(new Part(id, cloned[0].Diameter, cloned[0].Pitch, HardwareType.BOLT));
            cloned.RemoveAt(0);
        }
    }
}