Programming Puzzle

[Jatinder]

I found these questions on a web site and wish to share with all of u
out there,Can SomeOne Solve these Porgramming puzzles.
Programming Puzzles

Some companies certainly ask for these things. Specially Microsoft.
Here are my favorite puzzles. Don't send me emails asking for the
solutions.

Q1 Write a "Hello World" program in 'C' without using a semicolon.
Q2 Write a C++ program without using any loop (if, for, while etc) to
print numbers from 1 to 100 and 100 to 1;
Q3 C/C++ : Exchange two numbers without using a temporary variable.
Q4 C/C++ : Find if the given number is a power of 2.
Q5 C/C++ : Multiply x by 7 without using multiplication (*) operator.
Q6 C/C++ : Write a function in different ways that will return f(7) =
4 and f(4) = 7
Q7 Remove duplicates in array
Q8 Finding if there is any loop inside linked list.
Q9 Remove duplicates in an no key access database without using an
array
Q10 Write a program whose printed output is an exact copy of the
source. Needless to say, merely echoing the actual source file is not
allowed.
Q11 From a 'pool' of numbers (four '1's, four '2's .... four '6's),
each player selects a number and adds it to the total. Once a number
is used, it must be removed from the pool. The winner is the person
whose number makes the total equal 31 exactly.
Q12 Swap two numbers without using a third variable.
Given an array (group) of numbers write all the possible sub groups of
this group.
Q14 Convert (integer) number in binary without loops.

Q3,12 are similar , Q7 is simple & I know there answer For the Rest
please Help
Wiating for reply.

[Ioannis Vranos]

CBFalconer wrote:

int main (void)
{
if (printf("Hello World"))
{}
if (exit(EXIT_SUCC ESS))
{}
}

Illegal. No #include for prototype of variadic function, nor
EXIT_SUCCESS value, and exit is a void function. The compiler
should barf.

#include <stdio.h>
#include <stdlib.h>

int main (void)
{
if (printf("Hello World")) {}

/* Only needed for C90 compliance */
if (exit(EXIT_SUCC ESS),1){}
}


Regards,

Ioannis Vranos

[Ioannis Vranos]

Ioannis Vranos wrote:

Jatinder wrote:

Q3 C/C++ : Exchange two numbers without using a temporary variable.

Isn't the bitwise solution safe only for unsigned integrals?

I just checked the standard, it is safe for both integral and
enumeration types.


Regards,

Ioannis Vranos

[Ioannis Vranos]

Ioannis Vranos wrote:

However in both cases bitwise operations are guaranteed to be safe only
on unsigned integrals, so the above had better include the remark:
"where x is of unsigned integral type".

Just checked the C++98 standard, and they are valid for both integral
types and enumerations so what I said above is not needed.


Regards,

Ioannis Vranos

[Darrell Grainger]

On Sat, 26 Jun 2004, Jatinder wrote:

I found these questions on a web site and wish to share with all of u
out there,Can SomeOne Solve these Porgramming puzzles.
Programming Puzzles

Some companies certainly ask for these things. Specially Microsoft.
Here are my favorite puzzles. Don't send me emails asking for the
solutions.

[bunch of questions snipped]

Learn to use a search engine. The answer to the questions and many other
questions are readily available on the internet. You just need to learn to
search for them. Hint: http://groups.google.ca.

--
Send e-mail to: darrell at cs dot toronto dot edu
Don't send e-mail to vi************@ whitehouse.gov

[Jerry Coffin]

"Siemel Naran" <Si*********@RE MOVE.att.net> wrote in message news:<Fw******* *************@b gtnsc04-news.ops.worldn et.att.net>...

"Jerry Coffin" <jc*****@taeus. com> wrote in message
news:b2******** *************** **@posting.goog le.com...

Almost anything you'd normally do with iteration can also be done with
tail recursion.
What is "tail" recursion? Are there other types of recursion?

Tail recursion is when the recursive call is the final step of an
algorithm. If the recursive call isn't the final step, it's not tail
recursion. In some cases, of course, an algorithm with some other
execution pattern can be converted to a tail-recursive form, but
others can't (especially those that include two or more recursive
calls).
Any the question says not to use loops. But to me, recursion is a loop,
just expressed differently.
Both certainly express the concept of repeated execution of some set
of instructions. I'm less certain of characterizing all iteration as a
loop though.

[ ... ]
Are these methods faster than x*7 on modern processors?
Sometimes they are, other times they're not. The correct answer will
often depend as much on surrounding instructions as it does on the
processor.

Q6 C/C++ : Write a function in different ways that will return f(7) =
4 and f(4) = 7

If you want to get clever with boolean values, you could try:

int f(int x) {
return (x==7*4)+(x==4* 7);
}

Huh?

As has already been noted, I mis-parenthesized that. It should have
been "return (x==7)*4+(x==4) *7;" It's based on the fact that in C a
'true' result has the value 1, and a 'false' result has the value 0.
C++ has a type specifically for booleans, but for backward
compatibility it still allows them to be implicitly converted to
integer types.
I'm sure there are more variations as well.

Probably something with mod or %.

Maybe -- OTOH, that's sort of the basis of the 'x^3' version.
There's another. Have two iterators, first one pointing to first element,
the second pointing to the second. The second one is the fast iterator and
you increment it twice in each iteration. The first iterator is the slow
iterator and you increment it once in each iteration. If the list is not
circular the fast iterator will hit NULL at some point. If the list is
circular the fast iterator will equal to the slow iterator at some point.

Yes -- I'd seen that posted elsewhere so I didn't repost it, but it IS
pretty clever.

--
Later,
Jerry.

The universe is a figment of its own imagination.

[Wayne Rasmussen]

Siemel Naran wrote:

"Mabden" <mabden@sbc_glo bal.net> wrote in message news:B5uDc.6258

Maybe you would get the job for walking out...

That might be too out of the box :).

A job interview is for finding a match. The company is also under the
microscope. Would you really want to work for a company who gives this
as the big programming test?

[Gregory Pietsch]

js*******@sanch arnet.in (Jatinder) wrote in message news:<22******* *************** ****@posting.go ogle.com>...

I found these questions on a web site and wish to share with all of u
out there,Can SomeOne Solve these Porgramming puzzles.
Programming Puzzles

Some companies certainly ask for these things. Specially Microsoft.
Here are my favorite puzzles. Don't send me emails asking for the
solutions.

Q2 Write a C++ program without using any loop (if, for, while etc) to
print numbers from 1 to 100 and 100 to 1;

I'll try it in C, should be portable to C++:

#include <stdio.h>

int p(int x, int i)
{
(x > 100) && (i = -1);
(x > 0 && x < 101) && printf("%d\n", x);
(x > 0) && p(x + i, i);
return 1;
}

int main(void)
{
p(1, 1);
return 0;
}

Gregory Pietsch

[Foobarius Frobinium]

js*******@sanch arnet.in (Jatinder) wrote in message news:<22******* *************** ****@posting.go ogle.com>...

I found these questions on a web site and wish to share with all of u
out there,Can SomeOne Solve these Porgramming puzzles.
Programming Puzzles

Some companies certainly ask for these things. Specially Microsoft.
Here are my favorite puzzles. Don't send me emails asking for the
solutions.

Q3 (the same as the other you mentioned, basically) took me less than
a minute to solve, and I'm only 16:

/* vim:ts=4
*/

#include <stdio.h>

int main(void) {
int foo = 87;
int bar = 56;

foo += bar;
bar = foo - bar;
foo = foo - bar;

fprintf(stdout, "%i, %i\n", foo, bar);
}

Try other values for foo & bar, even negatives and zero.

You mentioned MS often use these sorts of puzzles to test their
programmers. I got an even better one to stump even the best MS
programmers:

/* vim:ts=4
*/

#include <stdio.h>

int main(void) {
int *foo = NULL;

fprintf(stdout, "%i\n", *foo);
}

What will happen if I compile and run this program??

[JKop]

Am I the only person here that thinks it's complete bullshit to think you
can swap the values of two variables without a temporary variable?! It
simply cannot be done. Why? Consider this, you have two containers, each of
capacity 3 litres. Each of them is filled with 2 litres of water. Swap the
water from the containers. Okay... let's just poor all of one of them into
the other. Mammy mammy! It was an accident, I didn't realize you can't put 4
litres of water into a 3 litre container.

Fools.
-JKop

[Joona I Palaste]

JKop <NU**@null.null > scribbled the following
on comp.lang.c:

Am I the only person here that thinks it's complete bullshit to think you
can swap the values of two variables without a temporary variable?! It
simply cannot be done. Why? Consider this, you have two containers, each of
capacity 3 litres. Each of them is filled with 2 litres of water. Swap the
water from the containers. Okay... let's just poor all of one of them into
the other. Mammy mammy! It was an accident, I didn't realize you can't put 4
litres of water into a 3 litre container. Fools.

It *can* be done! Not with all kinds of variables, but with unsigned
integer types, it's easy. Not one, but *two* ways to do it have been
shown in this thread. Of course it will break down if those variables
happen to share the same memory location, which can be the case if using
pointers and indirecting through them.

--
/-- Joona Palaste (pa*****@cc.hel sinki.fi) ------------- Finland --------\
\-- http://www.helsinki.fi/~palaste --------------------- rules! --------/
"I am not very happy acting pleased whenever prominent scientists overmagnify
intellectual enlightenment."
- Anon