18/11/22 04:04:02.81 dySjvlSp.net
>>632 Ruby
f = -> d {
[2, 5].each{|e| d /= e while d % e == 0}
return 0 if d == 1
r = 1; (1..d).find{|i| 1 == r = 10 * r % d}
}
%w[
1/3 10/2 988027/983 919/870473 1223/1476221 99998360006603/9999901 123412345/999999999 1234/555
].each{|e| n, d = e.split(?/).map(&:to_i); puts '%d/%d => %d' % [n, d, f[d / d.gcd(n)]]}
# =>
1/3 => 1
10/2 => 0
988027/983 => 982
919/870473 => 54288
1223/1476221 => 122816
99998360006603/9999901 => 1999980
123412345/999999999 => 9
1234/555 => 3