using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        int[] input = new int[] { 0,0,0,1,1,1,1,1,2,2 };

        Console.WriteLine(string.Join("\n",  input.DistinctWhere(x => x > 0)));

    }

}

​

public static class Extensions

{

    public static IEnumerable<T> DistinctWhere<T>(this IEnumerable<T> input, Func<T,bool> predicate)

    {

        HashSet<T> hashset = new HashSet<T>();

        foreach(T item in input)

        {

            if(!predicate.Invoke(item))

            {

                yield return item;

                continue;

            }

            if(!hashset.Contains(item))

            {

                hashset.Add(item);

                yield return item;

            }

        }

    }

}