Case 15 ?

I have no idea how you managed it, but I got false collisions with a random prime mod > 2*10^9. That's pretty good.

@rajat_007: Good day to you, well you can generate them yourself (you can use for example following [simplified] generator - to make random big testcases) http://pastebin.com/Es61Bez4 {I can't give-out judge data, so you have to do it more-or-less yourself :P }

GL ^_^

@rajat_007: Sorry, no clue - don't understand Java :/

Here is some NZEC topic [ http://stackoverflow.com/questions/24571469/getting-an-nzec-error-in-spoj-for-this-code ]

When I execute the file (it fails) locally, I get output "normally" so no clue where is problem.

It also says:

Note: Main.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

But I have no clue what it means :/

**EDIT → When I removed following lines:

for(int i=0;i<=n-k;i++)
{
String b=a.substring(i,i+k);
sh.add(b);
}

I got "WA" instead of "RTE" - so I guess there might be some "space overflow?" or something like that :O - dunno

Thank for the help ! I got AC :D