TinyCode competition - trial

[Riven]

I'm tempted to host some silly competion thingy about writing the smallest code to perform some I/O task.

I coded some really silly task, and I'd like you guys to check out whether there is anything dangerous possible.
If so, I'd be very grateful if you'd let me know as fast as possible.
I'm renting this server, and I wouldn't really like to get my account suspended.

I tried to isolate the running of tasks as much as possible, within the current JVM, but I might have to resort launching a new JVM to avoid any corruption of the HTTP-server-instance hosting this.

http://213.247.55.3:8484/compileandrun/


A (naive) solution for the task would be:

1   2   3   4   5   6   7   8

while(true) {   int a = in.read();   int b = in.read();   if((a|b)<0) break;   out.write(b);   out.write(a); }

108 bytes, linebreaks don't count (for readability reasons), but spaces do

Beat that! I didn't really raise the bar very high, did I..


Anyway, give it a try, and tell me if there's something I need to know.

[Riven]

Beat 62 bytes, and don't forget to be naughty.

[Riven]

I disabled uppercase characters... to catch the casual tester

1	System.exit(0);

This worked though:

1	\u0053ystem.exit(0);

Gimme your tricks..

Games published by our own members! Check 'em out!

[kappa]

ewww, no uppercase characters  , pretty much ends it for me.

[Riven]

Hey... how else would I keep it secure...

and... why would you need Classes in such tasks?



I'm glad you tried it though

[Abuse]

Beat 62 bytes, and don't forget to be naughty.

Got to 64bytes so far....

[Riven]

Way to go!

[kappa]

and... why would you need Classes in such tasks?

ah sorry my mistake, thought the task was to break the program

[Riven]

That too... and that stops like 99.9999% of all attacks.

[Abuse]

Got to 64bytes so far....

Haha, I'm such a muppet - that 64byte solution was actually 62bytes =)
I hadn't removed the declaration of the now unused b integer

Can't see a way of beating 62 though... atleast not yet =)

Games published by our own members! Check 'em out!

[Riven]

Darn.

[Riven]

A dead end... but I love it!

1	for(byte[]b={0,0,1};in.read(b,b[2]++&1,1)>0;out.write(b,0,b[2]*2&2));

(69 bytes)

[Abuse]

A dead end... but I love it!

1	for(byte[]b={0,0,1};in.read(b,b[2]++&1,1)>0;out.write(b,0,b[2]*2&2));

(69 bytes)

If you are going to break the defined contract of InputStream.read(byte[],int,int), by only checking for ">0" on the return type, then the 62 byte solution mentioned earlier can be trimmed to 61 bytes =)
(presumably your own 6[1/2] byte solution is exactly the same as mine?)

1	for(int a;(a=in.read())>0;out.write(in.read()),out.write(a));

[Riven]

>0 is not breaking the contract of InputStream.read(byte[],int,int)

This method blocks until input data is available, end of file is detected, or an exception is thrown.

it will never ever return 0.

Unless your set the thrid argument to 0

[noblemaster]

actually, I got 1 byte less (60 bytes):

1	for(int a;(a=in.read())>0;out.write(a))out.write(in.read());

ditto Abuse it's 61 bytes if you use >=0...

[Riven]

I guess this is good enough to turn into a bigger project

I wrote the http-server myself, so pretty much everything is possible.

Again, don't forget to mention the security-holes. Thank you.

[Riven]

1	for(int a;(a=in.read())>0;out.write(a))out.write(in.read());

I totally love the simplicity.

[Abuse]

oh yeah, nice spot 

[Abuse]

I totally love the simplicity.

I still think your 69byte solution is by far the most complicated =S

[Matzon]

isn't this flawed, since it only checks the validity of the first in.read?
-edit- ok, the string has pairs of bytes.

[Riven]

Second assignment available:
http://213.247.55.3:8484/compileandrun/?assignment=binaryshrink
73 bytes...


Third assignment available:
http://213.247.55.3:8484/compileandrun/?assignment=hex
86 bytes...

[Riven]

I'm adding a database now, to make accounts, and compete against eachother...

[markush]

Second assignment available:
http://213.247.55.3:8484/compileandrun/?assignment=binaryshrink
73 bytes...

72 bytes! muhahaha

To achieve it, you can replace the only space with a line break, and since that doesn't count its one byte off

[Riven]

Hehe... then I get 72 bytes too...

and I got 2 solutions:

1   2   3

for(int r=0,i=0,b=0;r>-1;b=b<<1|(r=in.read())&1) if(i++%8==0)out.write(b);

1   2   3   4   5   6

for(int r,i=0,b=0;(r=in.read())>0;) { b=b<<1|r&1; if(++i%8==0)out.write(b); }

The first is extremely not-done.

[Riven]

It's a nice loophole though, and I'll make sure I'll 'fix' that.

Like... only linebreaks allowed after a '{'



Could you show me your solution?

[markush]

Hehe... then I get 72 bytes too...

and I got 2 solutions:

1   2   3

for(int r=0,i=0,b=0;r>-1;b=b<<1|(r=in.read())&1) if(i++%8==0)out.write(b);

1   2   3   4   5   6

for(int r,i=0,b=0;(r=in.read())>0;) { b=b<<1|r&1; if(++i%8==0)out.write(b); }

The first is extremely not-done.

My is a bit different:

1   2   3   4   5

for(int c=0,i=0,x;(x=in.read())>0;c<<=1){ c|=x&1; if(++i%8<1)out.write(c); }

And 71 bytes with that:

1   2   3

for(int r=1,i=0,b=0;r>0;b=b<<1|(r=in.read())&1) if(i++%8==0)out.write(b);

[Abuse]

erm, am I missing something?
2 of the solutions above don't work?

They output a leading 0 to the output stream.

1   2   3

for(int r=1,i=0,b=0;r>0;b=b<<1|(r=in.read())&1) if(i++%8==0)out.write(b);

and

1   2   3

for(int r=0,i=0,b=0;r>-1;b=b<<1|(r=in.read())&1) if(i++%8==0)out.write(b);

[Martin Strand]

This doesn't output a leading zero but all ascii values are 0x100 too high. It looks ok on that web page though.   (70 bytes)

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for(int r=1,b=1; r>0; b=b<<1|(r=in.read())&1) if(b>255) { out.write(b); b=1; }

[Abuse]

This doesn't output a leading zero but all ascii values are 0x100 too high. It looks ok on that web page though.   (70 bytes)

1   2   3   4   5   6   7   8   9

for(int r=1,b=1; r>0; b=b<<1|(r=in.read())&1) if(b>255) { out.write(b); b=1; }

That's perfectly ok - the contract of OutputStream.write(int) dictates that only the bottom 8 bits are used anyway, so using the upper bits for signalling is pretty damn clever =)

[Abuse]

An adaption of the above (66 bytes!) :-

for(int
b=1;
(b=b<<1|(in.read()-48))>0;)
if(b>255){
out.write(b);
b=1;
}

And there is even a redundant ';' in the for, which I'm sure can be optimised away with some restructuring?