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- #!/usr/bin/perl
- # Author: Trizen
- # 17 February 2022
- # https://github.com/trizen
- # https://projecteuler.net/problem=451
- # Runtime: 55 seconds.
- use 5.010;
- use strict;
- use warnings;
- use ntheory qw(:all);
- sub l {
- (allsqrtmod(1, $_[0]))[-2];
- }
- my $sum = 0;
- foreach my $d (3 .. 2e7) {
- $sum += l($d);
- }
- say $sum;
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