C#CombinationAlgorithm

using System.Windows.Forms;

    public partial class Form1 : Form
    {
        private int size;
        private int pop;
        //private int k;
        private List<double> p = new List<double>();
        private List<double> m = new List<double>();
        private int counter;

        public Form1()
        {
            InitializeComponent();
        }
        private void button3_Click(object sender, EventArgs e)
        {
            pop = int.Parse(textBox1.Text);
            size = int.Parse(textBox3.Text);
            textBox1.ReadOnly = true;
            textBox3.ReadOnly = true;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (counter < pop)
            {
                p.Add(double.Parse(textBox2.Text));
                textBox2.Text = "";
                counter++;
                if (counter == pop)
                {
                    textBox2.ReadOnly = true;
                    button1.Hide();
                }
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            lessCombo(p, 0, 0, 0);
            string str = "";
            str += "Mean - Relative Frequency\n";
            if (m.Count > 100)
            {
                double[] array = new double[100];
                for (int b = 0; b < array.Length; b++)
                {
                    array[b] = m[b];
                }
                foreach (var group in array.GroupBy(n => n))
                {
                    str += string.Format("{0} - {1} \n", group.Key, group.Count());
                }
            }
            else
            {
                foreach (var group in m.GroupBy(n => n))
                {
                    str += string.Format("{0} - {1} \n", group.Key, group.Count());
                }
            }
            richTextBox1.Text = str;
            button2.Hide();
        }

        private void lessCombo(List<double> p, int i, int l, double a)
        {
            if (l == size)
            {
                double mean = a / size;
                m.Add(mean);

            }
            if (i < p.Count)
            {
                if (l != size)
                {
                    lessCombo(p, i + 1, l + 1, a + p[i]);
                    lessCombo(p, i + 1, l, a);
                }
            }
        }



    }