Project Euler – Problem 4

This problem allows us to use recursion and some type conversions.

using System;

namespace Problem4
{
    class MainClass
    {
        // Function to check if a number is a palindrome
        static bool isPalindrome(string numStr)
        {
            int numLen;
            numLen=numStr.Length;

            if (numLen<=1){
                return true;
            } else {
                return (numStr[0]==numStr[numLen-1] && isPalindrome(numStr.Substring(1,numLen-2)));
            }

        }

        // Main function
        public static void Main(string[] args)
        {
            int n1,n2;
            int maxVal=0;

            for (n1=100;n1<=999;n1++)
            {
                for (n2=n1;n2<=999;n2++)
                {
                    if (isPalindrome(Convert.ToString(n1*n2))){
                        if (n1*n2>maxVal){
                            maxVal=n1*n2;
                        }
                    }
                }
            }
            Console.WriteLine("The answer is {0}",maxVal);
        }
    }
}