project-euler/Sidef/095 Amicable chains.sf

#!/usr/bin/ruby

# Author: Trizen
# Date: 09 October 2016
# Translated: 21 March 2023
# https://github.com/trizen

# https://projecteuler.net/problem=95

# Runtime: ~2 minutes

var limit = 1e6
var chain = Hash()

for n in (1 .. limit) {

    var len  = 0
    var orig = n
    var seen = Hash()

    loop {
        n = n.aliquot
        break if (n > limit)
        break if seen.has(n)
        seen{n} = nil
        ++len
    }

    if (seen.has(orig)) {
        chain{len} := orig
    }
}

say chain{chain.keys.max_by { .to_i }}