39 lines
1.1 KiB
Perl
39 lines
1.1 KiB
Perl
package DDG::Goodie::Fibonacci;
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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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triggers any => 'fib', 'fibonacci';
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zci is_cached => 1;
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zci answer_type => 'fibonacci';
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primary_example_queries 'fib 7';
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secondary_example_queries 'fibonacci 33';
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description 'Returns the n-th element of Fibonacci sequence';
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attribution github => ['https://github.com/koosha--', 'koosha--'],
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twitter => '_koosha_';
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code_url 'https://github.com/duckduckgo/zeroclickinfo-goodies/blob/master/lib/DDG/Goodie/Fibonacci.pm';
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topics 'math';
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handle remainder => sub {
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s/^\s+//;
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s/\s+$//;
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return unless /^(?:what is the )?(\d+)(?:(?:th|rd|st)? number\??)?$/ && $1 <= 1470;
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my @fib;
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$#fib = $1;
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$fib[0] = 0;
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$fib[1] = 1;
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# Instead of calling a typical recursive function,
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# use simple dynamic programming to improve performance
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for my $i (2..$#fib) {
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$fib[$i] = $fib[$i - 1] + $fib[$i - 2];
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}
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my $suf = ordsuf($_);
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return "The $1$suf fibonacci number is ${fib[$1]} (assuming f(0) = 0).",
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html => "The $1<sup>$suf</sup> fibonacci number is ${fib[$1]} (assuming f(0) = 0).";
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};
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1;
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