using System;
using System.Collections;

namespace C_sharp_Console_Experimentation
{
	/// <summary>
	/// Summary description for MultiMap.
	/// </summary>
	public class MultiMap
	{

		public MultiMap()
		{
			//
			// TODO: Add constructor logic here
			//
		}

		public void InsertElement(object key, object inserter)
		{
			// Check to see if key already exists
			ArrayList elements = null;
			foreach(MultiMapPair mmp in multimap_)
			{
				if(key == mmp.key_)
				{
					elements = mmp.elements_;
					break;
				}
			}

			// If key already exists, add to the requisite group
			if(elements != null)
				elements.Add(inserter);

			// Else create a new pair and add
			else
			{
				MultiMapPair newPair = new MultiMapPair(key, inserter);
				multimap_.Add(newPair);
			}
		}

		// Get a list of elements associated with a given key
		public ArrayList WithKey(object key)
		{
			ArrayList elements = new ArrayList();

			// Check to see if key exists - if so, change elements
			foreach(MultiMapPair mmp in multimap_)
			{
				if(key == mmp.key_)
				{
					elements = mmp.elements_;
					break;
				}
			}
			return elements;
		}

		// Get a list of the keys used in the multimap
		public ArrayList Keys()
		{
			ArrayList keyArray = new ArrayList();
			foreach(MultiMapPair mmp in multimap_)
			{
				keyArray.Add(mmp.key_);
			}
			return keyArray;
		}

		#region Implementation Class


		private class MultiMapPair
		{
			public MultiMapPair(object key, object inserter)
			{
				key_ = key;
				elements_.Add(inserter);
			}
			public object key_;
			public ArrayList elements_ = new ArrayList();
		}


		#endregion Implementation Class


		#region Member Data

		// An arraylist of pairs
		private ArrayList multimap_ = new ArrayList();


		#endregion Member Data
	}
}

using System;
using System.Data;
using System.IO;
using System.Collections;

namespace C_sharp_Console_Experimentation
{
	/// <summary>
	/// Summary description for Class1.
	/// </summary>
	class Class1
	{
		/// <summary>
		/// The main entry point for the application.
		/// </summary>
		[STAThread]
		static void Main(string[] args)
		{
			//
			// TODO: Add code to start application here
			//

			MultiMap map = new MultiMap();

			map.InsertElement(1, "one1");

			ArrayList keys = map.Keys();
			foreach(object o in keys)
				Console.WriteLine(o.ToString());


			ArrayList elements = map.WithKey(1);
			foreach(object o in elements)
				Console.WriteLine(o.ToString());


			Console.Read();
		}
	}
}