project-euler/Sidef/061 Cyclical figurate numbers.sf

#!/usr/bin/ruby

# Author: Daniel "Trizen" Șuteu
# Date: 24 September 2017
# License: GPLv3
# Website: https://github.com/trizen

# https://projecteuler.net/problem=61

# Runtime: 1.782s

var(:trig, :square, :penta, :hexa, :hepta, :octa)

1000..9999 -> lazy.grep{ .digit(1) }.each { |n|
    var (h, t) = (String(n)/2 -> ...)

    trig{h}{t}   = true if is_polygonal(n, 3)
    square{h}{t} = true if is_polygonal(n, 4)
    penta{h}{t}  = true if is_polygonal(n, 5)
    hexa{h}{t}   = true if is_polygonal(n, 6)
    hepta{h}{t}  = true if is_polygonal(n, 7)
    octa{h}{t}   = true if is_polygonal(n, 8)
}

var a = [trig, square, penta, hexa, hepta, octa]

a.permutations { |*h|
    h.dig(0)         \\ next -> each_k { |ah|
    h.dig(0, ah)     \\ next -> each_k { |at|
    h.dig(1, at)     \\ next -> each_k { |bt|
    h.dig(2, bt)     \\ next -> each_k { |ct|
    h.dig(3, ct)     \\ next -> each_k { |dt|
    h.dig(4, dt)     \\ next -> each_k { |et|
    h.dig(5, et, ah) \\ next
        var nums = "#{ah}#{at} #{at}#{bt} #{bt}#{ct} #{ct}#{dt} #{dt}#{et} #{et}#{ah}".nums
        say "sum(#{nums.join(', ')}) = #{nums.sum}"
    }}}}}}
}