Re: Intersection and element counts
- To: mathgroup at smc.vnet.net
- Subject: [mg20771] Re: [mg20615] Intersection and element counts
- From: "Simons, F.H." <F.H.Simons at tue.nl>
- Date: Thu, 11 Nov 1999 00:22:46 -0500
- Sender: owner-wri-mathgroup at wolfram.com
Just for fun: the following solution works very fast when the two lists do
not contain numbers.
intersect[ list1_, list2_ ] := PolynomialGCD[ Times @@ list1, Times @@ list2
]
With
list1 = {a, b, b, a, c, d, b, b, c};
list2 = {a, b, d, b, b, a, d, c, c};
we obtain
a^2 b^3 c^2 d.
By applying List, followed by the simple substitution: Power[x_, n_] :>
Table[ x, {n}] and Flattening, the result may be given in the form of a
list, if desired.
Fred Simons
Eindhoven University of Technology