project-euler/Sidef/034 Digit factorials.sf

#!/usr/bin/ruby

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

# Find the sum of all numbers which are equal to the sum of the factorial of their digits.

# https://projecteuler.net/problem=34

# Runtime: 1.636s (previously: 2.673s)

var f = (0..9 -> map {|d| d! })

var sum = (3..1e5 `by` 2 -> grep { |n|
    n.digits.sum_by { f[_] } == n
}.sum)

say sum