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- #!/usr/bin/perl
- # Daniel "Trizen" Șuteu
- # License: GPLv3
- # Date: 11 May 2017
- # https://github.com/trizen
- # https://projecteuler.net/problem=129
- # Runtime: 1.086s
- use 5.010;
- use strict;
- use warnings;
- use ntheory qw(powmod gcd);
- for (my $n = 1e6 ; ; ++$n) {
- gcd($n, 10) == 1 or next;
- my $k = 0;
- for (my $sum = 0 ; ; ++$k) {
- $sum += powmod(10, $k, $n);
- $sum %= $n;
- last if $sum == 0;
- }
- if ($k + 1 > 1e6) {
- say "A($n) = ", $k + 1;
- last;
- }
- }
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