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using <tt>primeFactors</tt> from problem 35 to generate the list of prime factors in ascending order, and <tt>encode</tt> from problem 10 to compress this list to a list of numbers paired with their multiplicity.
 
using <tt>primeFactors</tt> from problem 35 to generate the list of prime factors in ascending order, and <tt>encode</tt> from problem 10 to compress this list to a list of numbers paired with their multiplicity.
  +
  +
  +
Without relying on <tt>encode</tt> from problem 10, but using <tt>group</tt> from <tt>Data.List</tt>:
  +
  +
<haskell>
  +
prime_factors_mult = map encode . group . primeFactors
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where encode xs = (head xs, length xs)
  +
</haskell>

Revision as of 08:02, 19 August 2012

(**) Determine the prime factors of a given positive integer.

Construct a list containing the prime factors and their multiplicity.

prime_factors_mult n = map swap $ encode $ primeFactors n
  where swap (x,y) = (y,x)

using primeFactors from problem 35 to generate the list of prime factors in ascending order, and encode from problem 10 to compress this list to a list of numbers paired with their multiplicity.


Without relying on encode from problem 10, but using group from Data.List:

prime_factors_mult = map encode . group . primeFactors
    where encode xs = (head xs, length xs)