473,838 Members | 1,637 Online
Bytes | Software Development & Data Engineering Community
+ Post

Home Posts Topics Members FAQ

Programming Puzzle

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.
Nov 14 '05
271 20376
In <40************ ***@nospam.com> Julie <ju***@nospam.c om> writes:
In <cb**********@o ravannahka.hels inki.fi> Joona I Palaste <pa*****@cc.hel sinki.fi> writes:
>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.
^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^ ^^^^^^^
Please describe (in code) a situation where two variables share the same memory
location.


Since you seem to be unable to understand plain English:

#include <stdio.h>

void swap(int *p, int *q) { ... }

int main()
{
int i = 10;
swap(&i, &i);
printf("%d\n", i);
return 0;
}

Try this code for different implementations of the swap function, using
a temp var and using in-place swapping. Compare the results.

This example is trivial, but the situation can realistically arise in more
complex algorithms.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de
Nov 14 '05 #81
Howard wrote:

"Julie" <ju***@nospam.c om> wrote in message
news:40******** *******@nospam. com...

>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.


Please describe (in code) a situation where two variables share the same

memory
location.


Just like described, using pointers. (References can also be used.)

void pswap( int* px, int* py )
{
*px = *px ^ ^py;
*py = *py ^ *px;
*px = *px ^ *py;
}

...calling code:...
int x = 3;
int* px = &x;
int* py = &x;
pswap( px, py );

-Howard


Yes, but the two variables are pointers, and they do not share the same memory
location -- they may *point* to the same location.

So, I still haven't seen two variables that share the same memory location. I
think that you can probably do it w/ placement new (C++ only!), but using (C++)
references or pointers, you can't have two variables that share the same memory
location.
Nov 14 '05 #82

"Julie" <ju***@nospam.c om> wrote in message
news:40******** *******@nospam. com...
Yes, but the two variables are pointers, and they do not share the same memory location -- they may *point* to the same location.

So, I still haven't seen two variables that share the same memory location. I think that you can probably do it w/ placement new (C++ only!), but using (C++) references or pointers, you can't have two variables that share the same memory location.


Geez, give me a break! What I've shown exhibits *exactly* the kind of
problem that can happen when trying to swap two integers using the xor
technique. Just because someone used terminology that suggested the two
variables themselves had the same memory location, surely you knew what was
meant! The problem is when both memory locations are the same, which can
happen if using pointers or references. That's all that was meant, not that
there were two *different* variables occupying the *same* memory.
-Howard

Nov 14 '05 #83
In comp.lang.c Joona I Palaste <pa*****@cc.hel sinki.fi> wrote:
job. That's all there was to it. No tests, no panel hearings, just a few
hours of talk.


I bet they saw your postings to comp.lang.c ;)

--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cybers pace.org | don't, I need to know. Flames welcome.
Nov 14 '05 #84
Dan Pop wrote:

In <40************ ***@nospam.com> Julie <ju***@nospam.c om> writes:
In <cb**********@o ravannahka.hels inki.fi> Joona I Palaste <pa*****@cc.hel sinki.fi> writes:

>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.

^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^ ^^^^^^^

Please describe (in code) a situation where two variables share the same memory
location.


Since you seem to be unable to understand plain English:

#include <stdio.h>

void swap(int *p, int *q) { ... }

int main()
{
int i = 10;
swap(&i, &i);
printf("%d\n", i);
return 0;
}

Try this code for different implementations of the swap function, using
a temp var and using in-place swapping. Compare the results.

This example is trivial, but the situation can realistically arise in more
complex algorithms.


No, I do not understand your version of plain English.

Just because you have two pointers that _point_ to the same address, this
doesn't mean that they (the variables here which are still the **pointers**)
share the same memory location.

Your definition of swap doesn't take to variables, it takes two addresses.
Even in your example in main, you are passing in the same pointer.

Show me a case of two separate variables that share the same memory location,
without using placement new. You can even use your version of 'plain English'.

Here is the point in my version of 'plain English': you can't have two
variables that share the same memory address (excluding placement new). So, if
the precondition for swap is that it operates on two variables, then it will
always work provided the precondition is met.
Nov 14 '05 #85
On 28 Jun 2004, Dan Pop wrote:
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 ^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^ [snip]

And the only good reason I can imagine is the failure to allocate memory
for a temporary object (some objects can be greater than others, some

^^^^^^^^^^^^^^^ ^^^

Your answer is completely irrelevant. ;-)

Tak-Shing

Nov 14 '05 #86

"Julie" <ju***@nospam.c om> wrote in message
news:40******** *******@nospam. com...
Here is the point in my version of 'plain English': you can't have two
variables that share the same memory address (excluding placement new). So, if the precondition for swap is that it operates on two variables, then it will always work provided the precondition is met.


So who ever sid the procondition was that you were swapping two non-pointer,
non-reference variables? If you're writing the swap as a function, you have
to use references or pointers, or else you'll only be swapping local copies.
That's what makes this an important consideration, because those pointer or
references parameters could be referring to the same memory location. The
swap function need to contain a check to handle that specific case.

-Howard

Nov 14 '05 #87
Julie wrote:
How can you _not_ remove an element from an array?

Here is a trivial case:

Since you use the malloc() family and this is cross posted to clc, I
assume you use C.

size_t count = 2;
int * array = (int *)malloc(sizeof (int) * count);

In C this casting is not needed.
array[0] = 42;
array[1] = 9000;
array = (int *)realloc(array , sizeof(int) * (--count));

In C this casting is not needed.


Regards,

Ioannis Vranos
Nov 14 '05 #88
On Mon, 28 Jun 2004, Tak-Shing Chan wrote:
On 28 Jun 2004, Dan Pop wrote:
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 ^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^ [snip]

And the only good reason I can imagine is the failure to allocate memory
for a temporary object (some objects can be greater than others, some

^^^^^^^^^^^^^^^ ^^^

Your answer is completely irrelevant. ;-)


To comp.lang.c++: sorry I didn't notice the cross-post at
the beginning. You can safely ignore my out-of-context reply.
What my post really amounts to is a (rather subtle) critique of
Dan Pop's lack of clarity in the replied-to post. [It took me
three to four readings to get his logic!]

Tak-Shing

Nov 14 '05 #89
On Mon, 28 Jun 2004, Christopher Benson-Manica wrote:
In comp.lang.c Joona I Palaste <pa*****@cc.hel sinki.fi> wrote:
job. That's all there was to it. No tests, no panel hearings, just a few
hours of talk.


I bet they saw your postings to comp.lang.c ;)


I thought he is a Java programmer? ;-)

Tak-Shing

Nov 14 '05 #90

This thread has been closed and replies have been disabled. Please start a new discussion.

Similar topics

270
3990
by: Jatinder | last post by:
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.
12
8490
by: G. | last post by:
Hi all, During my degree, BEng (Hons) Electronics and Communications Engineering, we did C programming every year, but I never kept it up, as I had no interest and didn't see the point. But now I really want to get back into it as I see a point with GNU/Linux. I want to get my old skills back and write something or help on some projects etc. I need some good books. I used to have one called "A Book On C", but sold it,
11
2230
by: John Salerno | last post by:
Similar to the Python Challenge, does anyone know of any other websites or books that have programming puzzles to solve? I found a book called "Puzzles for Hackers", but it seems like it might be a little advanced for me, and I've also read that it focuses too much on encryption and security issues and doesn't really have coding problems, exactly. But something like that book would be fun to have.
1
13120
by: xavier vazquez | last post by:
I have a problem with a program that does not working properly...when the program run is suppose to generate a cross word puzzle , when the outcome show the letter of the words overlap one intop of the other....how i can fix this the program look like this import java.util.ArrayList; import java.util.Random;
0
2031
by: xavier vazquez | last post by:
have a problem with a program that does not working properly...when the program run is suppose to generate a cross word puzzle , when the outcome show the letter of the words overlap one intop of the other....how i can fix this this run the random words for the program import javax.swing.JOptionPane; import java.util.ArrayList; import java.util.Random; public class CrossWordPuzzleTester {
44
3577
by: Jon Harrop | last post by:
Microsoft Research are developing a functional programming language called F# for .NET and I've been playing with it recently. I've uploaded some demos here: http://www.ffconsultancy.com/dotnet/fsharp/ I'm keen to see what Windows developers think of this language as we're considering using it to develop commercial applications on the Windows platform.
5
4477
by: ashish0799 | last post by:
HI I M ASHISH I WANT ALGORYTHMUS OF THIS PROBLEM Jigsaw puzzles. You would have solved many in your childhood and many people still like it in their old ages also. Now what you have got to do is to solve jigsaw puzzles using the computer. The jigsaw puzzle here is a square of dimension d (a puzzle with d^2 pieces) and the jigsaw pieces (all same dimensions) are of dimensions H x W (Which means the pieces have ‘H’ rows of ‘W’...
3
3213
by: oncue01 | last post by:
Word Puzzle Task You are going to search M words in an N × N puzzle. The words may have been placed in one of the four directions as from (i) left to right (E), (ii) right to left (W), (iii) up to bottom (S), or (iv) bottom to up (N). The program will print the starting place and the direction of each word. Limitations The number of words to be searched can be at most 100, the size of the puzzle N can be minimum 5 maximum 20....
4
20015
by: honey777 | last post by:
Problem: 15 Puzzle This is a common puzzle with a 4x4 playing space with 15 tiles, numbered 1 through 15. One "spot" is always left blank. Here is an example of the puzzle: The goal is to get the tiles in order, 1 through 15, from left to right, top to bottom, by just sliding tiles into the empty square. In this configuration, the goal would be to get the 14 and 15 to switch places, without affecting any of the other squares. Your...
13
3130
by: btkuhn | last post by:
Hi guys, I'm learning Python by teaching myself, and after going through several tutorials I feel like I've learned the basics. Since I'm not taking a class or anything, I've been doing challenges/programs to reinforce the material and improve my skills. I started out with stuff like "Guess my number" games, hangman, etc. and moved on to making poker and card games to work with classes. For GUIs I created games like minesweeper, and a...
0
9854
marktang
by: marktang | last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look ! Part I. Meaning of...
0
10903
Oralloy
by: Oralloy | last post by:
Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed. This is as boiled down as I can make it. Here is my compilation command: g++-12 -std=c++20 -Wnarrowing bit_field.cpp Here is the code in...
0
10584
jinu1996
by: jinu1996 | last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth. The Art of Business Website Design Your website is...
0
10290
tracyyun
by: tracyyun | last post by:
Dear forum friends, With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...
0
9425
agi2029
by: agi2029 | last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own.... Now, this would greatly impact the work of software developers. The idea...
0
7015
by: conductexam | last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one. At the time of converting from word file to html my equations which are in the word document file was convert into image. Globals.ThisAddIn.Application.ActiveDocument.Select();...
0
5681
by: TSSRALBI | last post by:
Hello I'm a network technician in training and I need your help. I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs. The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols. I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
0
5865
by: adsilva | last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
3
3131
bsmnconsultancy
by: bsmnconsultancy | last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.