Evaluate binomial coefficients: Difference between revisions
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(→{{header|Ruby}}: Added Array.combination.size) |
(→{{header|Perl 6}}: using a symmetry property) |
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<pre>10</pre> |
<pre>10</pre> |
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A useful optimization would use a symmetry property of the binomial coefficient: |
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<lang perl6>sub infix:<choose> { [*] ($^n ... 0) Z/ 1 .. min($n - $^p, $p) }</lang> |
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One drawback of this method is that it returns a Rat, not an Int. If we really worry about it, we can enforce the conversion: |
One drawback of this method is that it returns a Rat, not an Int. If we really worry about it, we can enforce the conversion: |
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<lang perl6>sub infix:<choose> { ([*] ($^n ... 0) Z/ 1 .. $^p).Int }</lang> |
<lang perl6>sub infix:<choose> { ([*] ($^n ... 0) Z/ 1 .. min($n - $^p, $p)).Int }</lang> |
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=={{header|PL/I}}== |
=={{header|PL/I}}== |
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