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Groups > comp.lang.java.programmer > #34315
| From | Nigel Wade <nmw@ion.le.ac.uk> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: Mathematics, Java, good enough |
| Date | 2016-05-17 12:56 +0100 |
| Message-ID | <dq0f7gFnat7U1@mid.individual.net> (permalink) |
| References | <nhesp7$hn7$1@dont-email.me> |
On 17/05/16 11:49, Duncan Idaho wrote:
> Hello again
>
> I have a question that involves mathematics. I agree that it's off topic but as I am writing in Java
> I thought I'd give it a go (tenuous I know but it's the best I've got).
>
> I'm dredging up set theory from the furthest reaches of my memory. I'll probably get it wrong.
> Homework? If only, that would mean I could have the last 50 years again ... perhaps not. %-)
>
> Anyway
>
> I have a set of characters S of cardinality C
> example
> if S = {a..z, 0..9, A..Z} then C = er, um ..,62.
>
> For any given result string X, X need not be a set.
>
> eg if L = 8 then
> "abcdefgh", "AAAAAAAA", "AABBCCDD" are all valid values for X
>
> how many strings of length L are possible from S
>
> I don't even know what to call the question and I probably won't understand the answer but it will be fun trying.
>
The answer is pretty simple. 62^8.
The reasoning is also pretty simple.
The first character has 62 possibilities.
The second character also has 62 possibilities, so the first 2 characters have 62*62 possibilities (62^2)
The third character also has 62 possibilities, so the first 3 characters have 62*62*62 possibilities (62^3)
In general, for L from S, the number of possibilities is S^L.
If you are not convinced, then just remove the letters and work with the numbers.
The first digit can be 0-9. The second digit can be 0-9, so the allowed values are 00-99. And so on. This ought to be
quite familiar. For 8 digits the range of possibilities would be 00000000-99999999.
I'm not sure of the specific name is, most likely combination of probabilities.
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Mathematics, Java, good enough Duncan Idaho <duncan@dunenoemail.com> - 2016-05-17 11:49 +0100
Re: Mathematics, Java, good enough Eric Douglas <e.d.programmer@gmail.com> - 2016-05-17 04:55 -0700
Re: Mathematics, Java, good enough Nigel Wade <nmw@ion.le.ac.uk> - 2016-05-17 12:56 +0100
Re: Mathematics, Java, good enough Nigel Wade <nmw@ion.le.ac.uk> - 2016-05-17 13:06 +0100
Re: Mathematics, Java, good enough Duncan Idaho <duncan@dunenoemail.com> - 2016-05-17 13:29 +0100
Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 09:54 -0400
Re: Mathematics, Java, good enough FredK <fred.l.kleinschmidt@gmail.com> - 2016-05-17 07:17 -0700
Re: Mathematics, Java, good enough FredK <fred.l.kleinschmidt@gmail.com> - 2016-05-17 07:29 -0700
Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 10:58 -0400
Re: Mathematics, Java, good enough Duncan Idaho <duncan@dunenoemail.com> - 2016-05-17 18:10 +0100
Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 14:02 -0400
Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 14:10 -0400
Re: Mathematics, Java, good enough Eric Douglas <e.d.programmer@gmail.com> - 2016-05-17 11:36 -0700
Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 16:12 -0400
Re: Mathematics, Java, good enough Eric Douglas <e.d.programmer@gmail.com> - 2016-05-17 13:56 -0700
Re: Mathematics, Java, good enough Gene Wirchenko <genew@telus.net> - 2016-05-17 14:13 -0700
Re: Mathematics, Java, good enough Duncan Idaho <duncan@dunenoemail.com> - 2016-05-18 05:06 +0100
Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 08:25 -0400
Re: Mathematics, Java, good enough Martin Gregorie <martin@address-in-sig.invalid> - 2016-05-17 12:24 +0000
Re: Mathematics, Java, good enough Duncan Idaho <duncan@dunenoemail.com> - 2016-05-17 18:15 +0100
Re: Mathematics, Java, good enough Jerry Stuckle <jstucklex@attglobal.net> - 2016-05-17 13:33 -0400
Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 14:09 -0400
Re: Mathematics, Java, good enough Gene Wirchenko <genew@telus.net> - 2016-05-17 14:17 -0700
Re: Mathematics, Java, good enough Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-05-17 17:49 -0400
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