But can it do this?
for n <- 10..98,
k <- (n + 1)..99,
rem(n, 10) != 0 && rem(k, 10) != 0,
d = gcd(n, k),
d > 1,
dn = digits(n),
dk = digits(k),
{a, b} <- intersection(dn, dk),
a != 0,
nr = div(n, d),
kr = div(k, d),
dab = gcd(a, b),
ar = div(a, dab),
br = div(b, dab),
nr == ar && kr == br do
{n, k, a, b}
end
Run
from Elixir (taken from
<https://github.com/greenfork/project_euler/blob/master/problem33.exs)>.
General ideas:
* Several iterating variables, definition at any time in the comprehension
* Assignments, checks - all is done linearly
In Nim it would be the following:
collect(newSeq):
for n in 10..98:
for k in (n+1)..99:
if n mod 10 != 0 and k mod 10 != 0:
let d = gcd(n, k)
if d > 1:
let
dn = digits(n)
dk = digits(k)
for (a, b) in intersection(dn, dk):
if a != 0:
let
nr = n div d
kr = k div d
dab = gcd(a, b)
ar = a div dab
br = b div dab
if nr == ar and kr == br:
(n, k, a, b)
Run
Nim variant is "more powerful" because we can do literally anything inside it
and it is much harder to understand because during list comprehension we don't
really want to do "literally anything", just a set of common actions.
