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Project Euler Problem 4

October 28th, 2009 Dallas 1 comment

This one was easier than I expected. I considered using some sort of lookup table to limit unnecessary calculations (103 x 104 = 104 x 103), but I’m pretty sure that would have only created more overhead.

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.

Find the largest palindrome made from the product of two 3-digit numbers.

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace Project_Euler_4
{
 class Program
 {
 
  static void Main(string[] args)
  {
   new Program();
  }
 
  Program()
  {
 
   int largestPalindromicProduct = 0;
 
   for (int i = 100; i <= 999; i++)
    for (int j = 100; j <= 999; j++)
    {
     int product = i * j;
 
     if (product > largestPalindromicProduct && isPalindromicNumber(product))
      largestPalindromicProduct = product;
    }
 
   Console.WriteLine(largestPalindromicProduct);
   Console.ReadKey();
  }
 
  bool isPalindromicNumber(int number)
  {
   string value = number.ToString();
 
   for (int i = 0; i < value.Length; i++)
   {
    if (!value[i].Equals(value[value.Length - 1 - i]))
     return false;
   }
 
   return true;
  }
 }
}
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