project-euler/Sidef/049 Prime permutations.sf

#!/usr/bin/ruby

# Daniel "Trizen" Șuteu
# License: GPLv3
# Date: 28 January 2017
# https://github.com/trizen

# https://projecteuler.net/problem=49

# Runtime: 0.265s

var perms = Hash()

for p in (primes(1000, 9999)) {
    perms{p.digits.sort.join} := [] << p
}

perms.each_v { |p|
    p.len >= 3 || next

    var diffs = Hash()
    for i in (0 .. p.end) {
        for j in (i+1 .. p.end) {
            diffs{p[j] - p[i]} := [] << (p[i], p[j])
        }
    }

    diffs.each_kv { |k,v|
        if (v.uniq.len == 3) {
            say "#{k}: #{v.uniq} -> #{v.uniq.join}"
        }
    }
}