1.cs

using System.Threading;

int[] m_forks = new[]
{
    1,
    1,
    1,
};

void TakeFork(int fid)
{
    lock (m_forks)
    {
        while (m_forks[fid] == 0);
        m_forks[fid] = 0;
    }
}

void ReturnFork(int fid)
{
    m_forks[fid] = 1;
}

void Philosopher(int id)
{
    while (true)
    {
        Console.WriteLine("[{0}] Thinking...", id);

        int secondForkId = (id + 1) % m_forks.Length;
        TakeFork(id);
        TakeFork(secondForkId);

        Console.WriteLine("[{0}] Eating with {0} and {1}...", 
            id,
            secondForkId);

        ReturnFork(id);
        ReturnFork(secondForkId);
    }
}

void Main()
{
    new Thread(new ThreadStart(() => Philosopher(0))).Start();
    new Thread(new ThreadStart(() => Philosopher(1))).Start();
    new Thread(new ThreadStart(() => Philosopher(2))).Start();
    
    Console.ReadKey();
}

Main();