Euler Problem 4

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.

Powershell Solution:

1. function Reverse-Text([string] $text) 
2. { 
3.     if($text.Length -eq 1) 
4.     { 
5.         return $text 
6.     } 
7.     else 
8.     { 
9.         return (Reverse-Text($text.Substring(1, $text.Length-1))) + $text[0] 
10.     } 
11. } 
12.  
13. $start = 999 
14. $end = 100 
15. $max_palindrome = 0 
16. for($num1 = $start; $num1 -ge $end; $num1--) 
17. { 
18.     for($num2 = $num1; $num2 -ge $end; $num2--) 
19.     { 
20.         $product = $num1*$num2 
21.         if($product.ToString() -eq (Reverse-Text($product))) 
22.         { 
23.             if($product -gt $max_palindrome) 
24.             { 
25.                 $max_palindrome = $product 
26.             } 
27.         } 
28.     } 
29. } 
30.  
31. echo $max_palindrome 

Note: The solution may not be the optimized one… just a quick hack… I’ll revisit later for optimization if time permits… :-)