Leetcode 10 - regular expression match - recursive solution - Very clear and simple recursive solution

Leetcode10_regularExpressionMatch_RecursiveSolution.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Leetcode10_regularExpressionMatch_recursive
{
    /// <summary>
    /// July 6, 2017
    /// Study recursive solution 
    /// code reference: 
    /// https://discuss.leetcode.com/topic/6183/my-concise-recursive-and-dp-solutions-with-full-explanation-in-c
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
        }

        public bool IsMatch(string s, string p)
        {
            if (p.Length == 0)
            {
                return s.Length == 0;
            }

            if (p.Length >= 2 && '*' == p[1])
            {
                // x* matches empty string or at least one character: x* -> xx*
                // *s is to ensure s is non-empty
                return (IsMatch(s, p.Substring(2)) ||
                        ((s.Length > 0) &&
                        (s[0] == p[0] || '.' == p[0]) &&
                        IsMatch(s.Substring(1), p)));
            }
            else
            {
                return (s.Length > 0) &&
                        (s[0] == p[0] || '.' == p[0]) &&
                        IsMatch(s.Substring(1), p.Substring(1));
            }
        }
    }
}