62 lines
1.6 KiB
Perl
Executable File
62 lines
1.6 KiB
Perl
Executable File
package DDG::Goodie::Fibonacci;
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# ABSTRACT: n-th Fibonacci number
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use strict;
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use DDG::Goodie;
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use Lingua::EN::Numbers::Ordinate qw(ordsuf);
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use Math::NumSeq::Fibonacci;
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use Math::BigInt;
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triggers any => 'fib', 'fibonacci';
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zci answer_type => 'fibonacci';
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zci is_cached => 1;
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sub answer {
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my ($text_ans, $title, $subtitle) = @_;
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return $text_ans, structured_answer => {
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data => {
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title => "$title",
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subtitle => "$subtitle"
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},
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templates => {
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group => 'text'
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}
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};
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}
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my $ith_limit = 25000; # limit for nth fibonacci numbers
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my $pred_limit = 10**22; # limit for if n is a fibonacci number
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my $fib_seq = Math::NumSeq::Fibonacci->new;
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handle remainder_lc => sub {
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# check "what is the nth fibonacci number"
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if (/^(?:what(?:'s| is) the )?(?<which>\d+)(?:st|nd|rd|th)?(?: number)?(?: in the (?:series|sequence))?\??$/ && $1 <= $ith_limit)
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{
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my $n = $+{'which'};
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my $val = $fib_seq->ith($n);
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my $suf = ordsuf($n);
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my $text_answer ="The $n$suf fibonacci number is $val (assuming f(0) = 0)";
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return answer($text_answer, $val, "$n$suf Fibonacci number");
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}
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# check "is n a fibonacci number"
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elsif (/^is (?<which>\d+) (?:a|in the)? ?(?:number|sequence)?\??$/ && $1 <= $pred_limit)
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{
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my $n = $+{'which'};
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my $val = $fib_seq->pred($n);
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my $is_fib = $val ? "is" : "is not";
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my $text_answer ="$n $is_fib a Fibonacci number";
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return answer($text_answer, $val ? "Yes" : "No", $text_answer);
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}
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else
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{
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return; # didn't match anything
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}
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};
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1;
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