Comments on: What Technical Tests Do You Give Potential Hires?

By: Rick Wargo

Rick Wargo — Mon, 14 Jun 2010 02:00:22 +0000

@David, creativity is key…languages are generally easily learned-the concepts are important.

By: David B

David B — Fri, 11 Jun 2010 15:56:42 +0000

Using a fictional english based language …

Function RevStr(GetStr as String)
For i=1 to Length(GetStr)
NewStr = NewStr & Left(Right(GetStr,i),1)
Next i
Return(NewStr)
End Function

By: Rick Wargo

Rick Wargo — Fri, 09 Apr 2010 14:49:26 +0000

That is basically identical to Shyam’s posting with the same problem; it doesn’t work on static strings. As soon as you attempt to change the string, an exception is raised:


Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_PROTECTION_FAILURE at address: 0x0000000100000eda

By: Rajendra Kumar Uppal

Rajendra Kumar Uppal — Tue, 30 Mar 2010 16:49:44 +0000

What about this?

char* mystrrev(char* s)
{
char* start = s;
char* left = s;
char c;
while (*s++);
s -= 2;
while (left < s)
{
c = *left;
*left++ = *s;
*s– = c;
}
return start;
}

By: Rick Wargo

Rick Wargo — Tue, 15 Dec 2009 22:09:05 +0000

That works well but limits itself to the type of input – won’t work well on a static string.

By: Shyam

Shyam — Mon, 14 Dec 2009 09:33:52 +0000

10 Lines code:
void rev(char *in)
{
char *en = in;
while(*en) en++;
en–;
while(in {
char temp=*en;
*en– = *in;
*in++=temp;
}
}

By: Rick Wargo

Rick Wargo — Fri, 11 Dec 2009 15:20:20 +0000

@Rajendra – Jigsaw actually the in-place solution correct – and it works for both even and odd length strings.

By: Rick Wargo

Rick Wargo — Fri, 11 Dec 2009 15:16:13 +0000

@Rajendra – Mark actually has it correct. This pattern is also very common in recursive functions: depending on when you call yourself, it completely changes the output (start vs end of routine). So by saying “string.charAt(i) + result” reverses the string; if he would have put “result + string.charAt(i)” then he would have reproduced the string.

By: Rajendra Uppal

Rajendra Uppal — Tue, 24 Nov 2009 19:32:05 +0000

CAN WE DO IT WITHOUT USING ANOTHER STRING?
I mean, what if the input string is large say 1000 chars long than according to the solutions provided above you are using extra space(in bytes) of equal to length of the string.

@Rick
How can we please come out of the space time complexity tread-off?

@Mark
You are just copying the input string and returning it back!!

@Anuj
You are just printing it reversely!!

By: Mark Klinchin

Mark Klinchin — Mon, 09 Nov 2009 05:52:35 +0000

Hi Rick, it’s very cute task for the interview. You have interesting observations about it. Here is Java version for your collection. It was nice to meet you at SPS Philly. Mark.

private static String reverse(String string) {
String result = “”;
for(int i=0; i result = string.charAt(i) + result;
return result;
}