project-euler/Sidef/004 Largest palindrome product.sf

#!/usr/bin/ruby

# Daniel "Trizen" Șuteu
# Date: 09 October 2017
# https://github.com/trizen

# 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.

# https://projecteuler.net/problem=4

# Runtime: 0.175s

func largest_palindrome_product (n) {

    for k in ((10**n - 1) `downto` 10**(n-1)) {
        var t = Num("#{k}#{Str(k).flip}")

        t.divisors.each {|d|
            if ((d.len == n) && ((t/d).len == n)) {
                return [d, t/d, t]
            }
        }
    }
}

say largest_palindrome_product(2)
say largest_palindrome_product(3)