project-euler/Sidef/038 Pandigital multiples.sf

#!/usr/bin/ruby

# Author: Daniel "Trizen" Șuteu
# License: GPLv3
# Website: https://github.com/trizen

# What is the largest 1 to 9 pandigital 9-digit number that can be formed as the concatenated product of an integer with (1,2, ... , n) where n > 1?

# https://projecteuler.net/problem=38

# Runtime: 1.044s (previously: 1.644s)

func valid_num(n) {
    var digits = n.digits

    return false if (digits.contains(0))
    return false if (digits.unique.len != n.len)

    return true
}

var max = 0
for i in (1..10000) {
    valid_num(i) || next

    var prod = Str(i)
    for n in (2..9) {

        var last = prod
        prod += Str(n*i)

        if (!valid_num(Num(prod))) {
            last = last.to_i
            max = last if (max < last)
            break
        }
    }
}

say max