No. If there were an ENTER, you would have to press 4 keys for each of the 625 possible codes, 2500 number-presses in all.
Since there is no ENTER, you can, if you're careful, try a new code with each button-press. But you have to put in the first 3 digits with no chance of opening the lock; thereafter you can try at most one new code per key entered, so the minimum number of key-presses is 3+625=628 (I mistyped 629 in my earlier post). Henry Rich > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Mark > D. Niemiec > Sent: Wednesday, June 25, 2008 11:11 PM > To: [email protected] > Subject: Re: [Jprogramming] Applied J: burglarly > > "Henry Rich" <[EMAIL PROTECTED]> wrote: > > We must be solving different problems. There are 5^4=625 different > > combinations for 4 pushes of 5 buttons; so the shortest possible > > answer is 629 characters. > > If there were a break (say, pressing Enter) between each > group of buttons, > 625 presses should get all combinations. However, since there > is no break, > sequences can overlap, greatly reducing the number of presses. Since > each button can be used in up to 4 sequences, this places a > lower bound > of 160 presses (4+>.625/4) on the solution. > > If repeats are not allowed, this reduces the number of allowable codes > to 320, and imposes a lower bound of 84 on the solution. > > $ ((*./@:(2&(~:/\))&>)#]) ,{4$<'abcde' > 320 > > -- Mark D. Niemiec <[EMAIL PROTECTED]> > > ---------------------------------------------------------------------- > For information about J forums see > http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
