擅长:python、mysql、java
<p>Ruby和Python的其他选项。在</p>
<p>对于Ruby:</p>
<pre><code>cf = {:metre=>{:kilometre=>0.001, :metre=>1.0, :centimetre=>100.0}, :litre=>{:litre=>1.0, :millilitre=>1000.0, :imperial_pint=>1.75975}}
from = :litre
to = :millilitre
cf.select { |k, v| ([from, to] - v.keys).empty? }.keys
#=> [:litre]
</code></pre>
<p>对于Python:</p>
^{pr2}$