Re: Re: how to get the longest ordered sub
- To: mathgroup at smc.vnet.net
- Subject: [mg103240] Re: [mg103212] Re: [mg103158] how to get the longest ordered sub
- From: DrMajorBob <btreat1 at austin.rr.com>
- Date: Fri, 11 Sep 2009 05:27:31 -0400 (EDT)
- References: <200909101124.HAA18266@smc.vnet.net>
- Reply-to: drmajorbob at yahoo.com
That's elegant... but Subsets gets HUGE if lst gets only slightly large. Bobby On Thu, 10 Sep 2009 06:24:15 -0500, Bob Hanlon <hanlonr at cox.net> wrote: > > lst = {1, 8, 2, 4, 3, 5}; > > Select[oss = Select[Subsets[lst], OrderedQ], > Length[#] == Max[Length /@ oss] &] > > {{1, 2, 4, 5}, {1, 2, 3, 5}} > > Select[oss = Select[Subsets[lst], OrderedQ[Reverse[#]] &], > Length[#] == Max[Length /@ oss] &] > > {{8, 4, 3}} > > > Bob Hanlon > > ---- a boy <a.dozy.boy at gmail.com> wrote: > > ============= > Thank all! your answers are right! > However,what I need is the longest not-strict ordered items of a given > list > L, not a segment of L. For example, > {1,8,2,4,3,5} -- ascending--> {1,2,4,5} > {1,8,2,4,3,5} --descending-->{8,4,3} > > Because when I think this question ( > http://groups.google.com/group/comp.soft-sys.math.mathematica/browse_thread/thread/f82401b1a517310c/9ca72a83a2313f50?lnk=gst&q=a.dozy.boy#9ca72a83a2313f50 > ): > For any integer k and 3^k, suppose 2^j is the closest to 3^k, > Gap[k]=| 3^k-2^j| is the subtraction . > > Gap = Function[k, x = k*Log[2, 3]; Min[3^k - 2^Floor[x], 2^Ceiling[x] > - > 3^k]]; > list=Table[{i, Gap[i]}, {i, 1, 5000}] > > I want to find a non-strict decreasing items of {Gap[i]} . > > > On Wed, Sep 9, 2009 at 7:53 PM, Fred Simons <f.h.simons at tue.nl> wrote: > >> a boy wrote: >> >>> how to get a (strict or not-strict)decreasing sub sequence of a list? >>> ---------------- >>> increasing ? >>> >>> >>> >>> >> lst=RandomInteger[{1,100}, {5000}]; >> >> With[{sublists=Split[lst, #1<#2&]}, >> With[{m=Max[Length /@ sublists]}, >> Select[sublists, Length[#]==m&]]] >> >> {{3,19,22,33,51,66,89,95}} >> >> Fred Simons >> Eindhoven University of Technology >> > > -- > > Bob Hanlon > > -- DrMajorBob at yahoo.com
- References:
- Re: how to get the longest ordered sub sequence of a
- From: Bob Hanlon <hanlonr@cox.net>
- Re: how to get the longest ordered sub sequence of a