#!/usr/bin/perl
use strict;
use warnings;
use bignum ( p => -9999 );      # this is huge, by the way

my $limit = shift;      # 1000 for project euler
my $longest = 1;
my $value;

for my $val (1..$limit) {
        my $frac = 1/$val;
        if (reverse($frac) =~ /(\d+)\1+/) {
                my $longestSubChain = reverse($1);
                if ($longestSubChain =~ /(\d+?)\1+/) {
                        if (length($1) > $longest) { $longest = length($1); $value = $val; }
                }
        }
}

print "d = $value\n";
print "Longest recurring cycle: $longest";