Need some help ASAP

[varma]

Hi i need some help in creating this program,




Program, in a standard programming language (e.g. Java), a fast and simple solution to the following problem without using any regular expression or pattern matching utilities. Given a non-finite stream of characters, output an "A" if the characters "xxx" are found in exactly that sequence. If the characters "xMx" are found instead, output a "B". Do not re-process characters so as to output both an “A” and a “B” when processing the same input. For example:

1. The following input xxMxMxxxMxxx would produce the following output: BAA

2. The following input xxxMxMxxxxMMxMxMx would produce the following output: ABAB



thanks in advance.

[Fubarable]

Here are Some appropriate links from JavaRanch:
ShowSomeEffort
NotACodeMill
DoYourOwnHomework

[Lil_Aziz1]

This is what I was thinking: make a while loop that starts at the first char. Look at the first 3 chars. If they are equivalent to A or B result, move onto the 4th char. If they are not, move onto the 2nd character. Then compare the 2nd, 3rd, and 4th char. If they match, move onto the 5th char. If not, move onto the 3rd char and so on. Hope that helps. ;)

[collin389]

You could also use patterns: Java Tutorials: Regex

[Kligham]

You could also use patterns: Java Tutorials: Regex

He literally said:

without using any regular expression or pattern matching utilities

[collin389]

Oh, I didn't read his post... Just now noticed that he is getting input from an infinite stream of chars so he will have to use a buffer.

[JosAH]

Given a non-finite stream of characters, output an "A" if the characters "xxx" are found in exactly that sequence. If the characters "xMx" are found instead, output a "B". Do not re-process characters so as to output both an “A” and a “B” when processing the same input. For example:

1. The following input xxMxMxxxMxxx would produce the following output: BAA

2. The following input xxxMxMxxxxMMxMxMx would produce the following output: ABAB

There is no way the first system produces that output. That is a Semi Thue System and has to obey the rules you defined; what is the system to do with the prefix "xx"? There is no matching rule. Please restate your rules and/or examples.

kind regards,

Jos

[Supamagier]

There is no way the first system produces that output. That is a Semi Thue System and has to obey the rules you defined; what is the system to do with the prefix "xx"? There is no matching rule. Please restate your rules and/or examples.

kind regards,

Jos

xxMxMxxxMxxx
BAA?

[JosAH]

xxMxMxxxMxxx
BAA?

No, you'd get xBMAMA

kind regards,

Jos

[Supamagier]

He said output, not replace.

Anyway, varma, you've gotta show us what you've done so far or at least what you've tried. Really, nobody is gonna do your homework. We're here to help.

[JosAH]

He said output, not replace.

Sorry, my bad; using the String.indexOf( ... ) method will be enough then.

kind regards,

Jos

[AndreB]

a simple final state machine would be enough i think. do your own simulat0r :-P
(also it will be equal to regular expressions)