using System;

using System.Xml;

using System.Xml.Serialization;

using System.IO;

using System.Linq;

using System.Collections;

using System.Collections.Generic;

using System.Xml.Linq;

public class Program

{

    public static void Main()

    {

        Dictionary <string, int?[]> documentFileList  = new Dictionary <string, int?[]> ();

        documentFileList.Add("hello", new int?[] {1,2,3, null });

        documentFileList.Add("world" ,new int?[] {4,5,6 });

        documentFileList.SelectMany(x=>x.Value.Where(v=>v.HasValue).Select(s=> new KeyValuePair<string, int>(x.Key, s.Value))).Dump();

    }   

}

​

​

​

​

​