Example Solution for https://exercism.org/tracks/csharp/exercises/dominoes

Dominoes.cs

using System;
using System.Linq;
using System.Collections.Generic;

public static class Dominoes
{
    public static bool CanChain(IEnumerable<(int, int)> dominoes)
    {
        if (dominoes.Any())
            return CanChain(dominoes.ToArray().AsSpan());
        else
            return true;   
    }

    private static bool CanChain(Span<(int DotCount1, int DotCount2)> dominoes)
    {
        var firstDominoFace = dominoes[0];

        if (dominoes.Length == 1)
        {
            return firstDominoFace.DotCount1 == firstDominoFace.DotCount2;
        }

        for (int i = 1; i < dominoes.Length; ++i)
        {
            var currentDominoFace = dominoes[i];

            if (currentDominoFace.DotCount1 == firstDominoFace.DotCount1)
            {
                dominoes[i].DotCount1 = firstDominoFace.DotCount2;
                if (CanChain(dominoes.Slice(start: 1))) return true;
            }

            if (currentDominoFace.DotCount1 == firstDominoFace.DotCount2)
            {
                dominoes[i].DotCount1 = firstDominoFace.DotCount1;
                if (CanChain(dominoes.Slice(start: 1))) return true;
            }

            dominoes[i].DotCount1 = currentDominoFace.DotCount1;
        }

        return false;
    }
}