如何在C#中计算PI？

using System;

class Program
{
    static void Main()
    {
        int total = 1000000;
        int circle = 0;
        Random rand = new Random();

        for (int i = 0; i< total; i++)
        {
            double x = rand.NextDouble();
            double y = rand.NextDouble();

            if (x * x + y * y <= 1)
            {
                circle++;
            }
        }

        double pi = 4.0 * circle / total;
        Console.WriteLine("π ≈ " + pi);
    }
}

using System;

class Program
{
    static void Main()
    {
        int iterations = 1000000;
        double pi = 0.0;

        for (int i = 0; i< iterations; i++)
        {
            double term = Math.Pow(-1, i) / (2 * i + 1);
            pi += term;
        }

        pi *= 4;
        Console.WriteLine("π ≈ " + pi);
    }
}