project-euler/Sidef/182 RSA encryption.sf

#!/usr/bin/ruby

# Daniel "Trizen" Șuteu
# Date: 14 January 2017
# License: GPLv3
# https://github.com/trizen

# https://projecteuler.net/problem=182

# Runtime: 18.471s (previously 45.963s)

var p = 1009
var q = 3643

var phi = (p - 1)*(q - 1)
var sum = 0

for e in (2 .. phi-1) {
    if (e.is_coprime(phi)) {
        if ((gcd(e - 1, p - 1) == 2) &&
            (gcd(e - 1, q - 1) == 2)) {
            sum += e
        }
    }
}

say sum