Stackoverflow interview problem 38384537 "minimum unique array sum", C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

// see problem at http://stackoverflow.com/questions/38384537/minimum-unique-array-sum/

using System;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            F();
        }

private static int F()
        {
            int[] a = {2, 2, 2, 3, 8, 9}; // sorted list
                
            int n = 0; // num
            int p = 0; // prev; zero is an invalid value in the list
            int q = 0; // queue
            int s = 0; // sum
            
            for (int i = 1; i < a.Length; i++)
            {
                n = a[i];
                if (n == p)
                {
                    q++; // increment queue on duplicate number
                }
                else
                {
                    // for every hole between array values, decrement queue and add to the sum
                    for (int j = 1; q > 0 && j < n - p; j++)
                    {
                        q--;
                        s += p + j;
                        Console.WriteLine(p + j);
                    }
                    s += (p = n);
                    Console.WriteLine(n);
                }
            }
            // flush the queue
            for (; q > 0; q--)
            {
                s += n++;
                Console.WriteLine(n);
            }

Console.WriteLine("Sum: {0}", s);
            return s;
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,12 sec, absolute running time: 0,09 sec, cpu time: 0,11 sec, average memory usage: 12 Mb, average nr of threads: 3