Re: A list of numbers without "73"

*To*: mathgroup at smc.vnet.net*Subject*: [mg63012] Re: [mg63005] A list of numbers without "73"*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sun, 11 Dec 2005 04:56:34 -0500 (EST)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

Clear[S,S2]; S[1]=Range[1, 9]; S[i_?Positive]:=S[i]= Delete[Union[Table[ k*(1-Boole[StringMatchQ[ToString[k], "*73*"]]), {k, 10^(i-1), 10^i-1}]], 1]; S2[1]=Range[1, 9]; S2[i_?Positive]:=S2[i]= DeleteCases[Range[10^(i-1), 10^i-1], _?(StringMatchQ[ToString[#], "*73*"]&)] And@@Table[S[i]==S2[i],{i, 4}] True Timing[S[6]][[1]] 36.1983 Second Timing[S2[6]][[1]] 28.961 Second %/%% 0.800065 S[6]==S2[6] True Bob Hanlon > > From: "Thomas Schmelzer" <thomas.??? at balliol.ox.ac.uk> To: mathgroup at smc.vnet.net > Date: 2005/12/10 Sat AM 06:03:40 EST > Subject: [mg63012] [mg63005] A list of numbers without "73" > > Experts, > > S(i) should be a list of positive integers without the substring "73". > > My code seems to be very inefficient. I multiply all numbers with 0 if they > contain "73", sort the new list, make the union (remove double elements) and > delete the first element. Therefore it is necessary to use an if statement > in order not to delete the first element of the numbers 1-9. Any more > sophisticated ideas? > > L := Table[k, {k, 1, 9}] > > S[i_] := S[i] = > If[i == 1, L, > Delete[Union[ > Table[k*(1 - Boole[StringMatchQ[ToString[k], "*73*"]]), {k, > 10^(i - 1), 10^i - 1}]], 1]] > > > > Best > > Thomas > > > > >