local bigint = require "pluto:bigint"

class Factorial
    static function iterative(n)
        local fact = bigint.new(1)
        if n < 2 then return fact end
        for i = 2, n do fact *= bigint.new(i) end
        return fact
    end

    static function recursive(n)
        if n < 2 then return bigint.new(1) end
        return bigint.new(n) * Factorial.recursive(n - 1)
    end
end

local function commatize(n)
    local s = n:tostring()
    local zero = bigint.new(0)
    if n < zero then s = s:sub(2) end
    for i = #s - 3, 1, -3 do
        s = s:sub(1, i) .. "," .. s:sub(i + 1)
    end
    if n >= zero then return s end
    return "-" .. s
end

local n = 24
print($"Factorial({n}) iterative -> {commatize(Factorial.iterative(n))}")
print($"Factorial({n}) recursive -> {commatize(Factorial.recursive(n))}")