Tuesday, March 12, 2013

New Technical Terminology Puzzle - JobPuzzles.Com

Everyone around wants to use me.
Everyone wants to share things with me.
I will make them there things delivered anywhere.
Earlier also they had people similar to me, but they were kept close.
I am far, and not close.
Yet everyone wants me.
Who am I??

I will post later. This is easy

Set HSB of Unsigned Integer Zero

On My one of the Interview Stint with Adobe, I read a programming or technical puzzle by Mr. Denis ZabavchikI have also been recommended this puzzle by my seniors presently scattered in Sunny Vale, Palo Alto, and Bangalore.
The question is to  set the highest significant bit of an unsigned integer to zero. You are intended to write a macro for that. Comeon, Techies. Get the Job Done!!

 #define Set_HSB_ZERO(h) \ 
(h&=(h>>1)|(h>>2), \
h|=(h>>2), \
h|=(h>>4), \
h|=(h>>8), \

Little House, All Alone, Break Wall to Live : Classic riidle

Now there is one childish Riddle.
Who knows you get to answer this at certain interviews. Technically because your interviewers might be reading this Website. :)

I have a little house in which I live all alone.
It has no doors and windows.
And if I want to go out I must break through the wall.
Though I am living in my house, but for actual living I have to go out!!
Who am I??

It is chicken before birth. Living in Egg.:)

Solution to Seven Pieces, Two Cuts - Gold Puzzle at JobPuzzles.Com

This post is Solution to Seven Pieces, Two Cuts - Gold Puzzle at JobPuzzles.Com
For question Refer to :
Original 7 Piece 2 Cuts Gold Bar Paying Problem at JobPuzzles.Com

What you can do is to divide the 7 piece gold bar to make a piece of following sizes:
-->1 part (Say A)
-->2 part  (Say B)
You have used your two cuts, that you were allowed to do
--> third will be automatically of 4 parts  (Say C)

And now you can pay him at end of each day by help of these divided parts.
For eg.
On First Day--> Give A
On Second Day--> Take A give B
On Third Day--> Give A
On Fourth Day--> Take A and B, and give C
Now you know the answer. So complete it.

Pointer Arithmetic Interview Puzzle at Job Puzzles.Com

Pointer Arithmetic Question for technical interviews.
I am also giving solution to this, but it is adviced to see the solution only after trying for sometime.

Question: What will be the output of following code and how.

void main()
int *p,*q;
p=(int *)40;
q=(int *)60;

It is 6-40=20
and then 20/2 =10
Think How!!

Seven Pieces, Two Cuts - Gold Bar Puzzle

You have engaged someone for seven days for some work. And, you have a gold bar to pay him.
(God!! what is that work?? Anways that is not my puzzle!!)

The gold bar is divided into seven connected pieces. That is you can easily break them in seven equal pieces, but still they are loosely joined.
You have to pay him a piece of gold at the end of every day.

Question: You can make only two breaks in the gold bar. Then how will you pay him.

I have dedicated another post for the solution.
Solution to the 7 Pieces 2 Cuts Gold Bar Paying Problem at "Puzzles in Job Interviews"
First think and try to solve before jumping to the answer.

Not Tells, Not Knows, Not Wants - what???

Tickling Riddle:

You will be amazed to know that this Puzzle which has been around over the internet, has been asked by one candidate appearing for a Financial High Profile Job Function.

One who has it does not tell it. 
One who takes it does not know it. 
One who knows it does not want it. 
What is that??

Its Money!!

Confused? I am also Kidding. It is Counterfeit Money!!

Equal Division of Cake with Rectangular Piece Removed

You are given a rectangular cake with a rectangular piece removed.
The piece removed can be any size or orientation.
How will you cut the remaining cake into two equal halves with one straight cut.


|              |
|      ____|

Solution: Now if you want a witty answer, just cut the cake at its width. ie. Look the cake fro its side. Lets say cake is 10 cm thick, cut it from 5ck thickness mark
There is one more answer for Pure mathmaticians.

Twice in week, Once in Year

This is Second in a "Week Year Minute But Not : Classic Word Riddles"

What comes twice in a week, but once in a Year?

In a different Post:

Solution To Twice in Week, once in Year Puzzle at JobPuzzles.Com

Solutions to "Week Year Minute But Not : Classic Word Riddles"

This is answer to previous puzzles:

Question 1:
What comes once in a minute, twice in a moment, but never in a hundred thousand years?
The Letter 'M'

Question 2:
What comes twice in a week, but once in a Year?
Come on, Now that is easy!!
The Letter 'E'

Run and Wet, Still but Dry Puzzle

Job Puzzle:
There were five men went to church.
Suddenly, it started to rain. 

The four men who ran got wet,
And the one that stood still stayed dry.



Might be they were 4 men and a dead man in coffin. So he was dry.

I have an exclusive answer too, that relates to Management Professionals. Can anyone guess??

once in a minute, twice in a moment, but never in a hundred thousand years

This is First in a "Week Year Minute But Not : Classic Word Riddles"

What comes once in a minute, twice in a moment, but never in a hundred thousand years?

In a different Post:
Solution to Once in Minute but not in thousand Years Riddle at JobPuzzles.Com

Gets Wet While Drying

What gets wet while drying.

One answer is a Towel

Is there other. Let us see your wit here... 

100 Camels 7 Poles Solution

There was a question asked in Earlier 100 camels 7 poles Question On this Website

Question: How can you tie 100 camels in 7 poles such that each pole has odd numbers of camels.


See when there are odd number of poles, you cannot tie odd numbers of camels on each pole to get an even number 100

So, it is not possible

Come from Mine, Caged in Wood : Classic

I come from a mine...
and caged in a wooden case...
A case from which I am never released...
and yet I am used by almost everybody.
And before using me people try to release me from my case.

But after sometime, I again go into that wooden case.


Its a Pencil Lead.

You have to sharp it befor using
And then it again gets used up, and goes inside the wooden wrap.

Tie 100 Camels in 7 poles : Classic

Now this puzzle has been around for several years. I learned this even before I knew these can also be asked in any interviews.

I don't remember who (Mom, Dad, or relative) asked me this. But here it goes. And, Yes ; This has been asked recently in a US Startup firm here in Bay Area

Question: How can you tie 100 camels in 7 poles such that each pole has odd numbers of camels.


See this is a simple question.
I want you to think.
And I dont want anyone asking this to me over the email, so I have separate blog post for solution.
Discuss here, solve here or goto following for the solution!!
Solution to 100 Camels 7 Pole problem at JobPuzzles.Com

Algorithm to Reverse Linked List - Classic

This is a classic programming puzzle, posed to many and different palces.

Companies in love with this question: Adobe, Microsft, Amazon, Microsoft
Google has changed this question. (in some other post)
Facebook asks an implementation of this in another problem (That Facebook puzzle and its solution some other time)


start : iterative loop 
curr->next = prev; 
prev = curr;
curr = next;
next = curr->next

Another solution can be by using Recursive function:
Just watch the "Base condition" of this algorithm
if (ptr->next == NULL)
return ptr;
temp = recursive_solution(ptr->next);
temp->next = ptr;
return ptr;

Two People Running same speed. Yet who wins - Time and distance Classic Puzzle

Silvia and Charlotte have exact speeds for walking and running - neither Silvia outwalks Chalotte, nor Charlotte outruns Silvia.Technically, same speed.
But for a given distance, Silvia runs half the time, then walks another half. 
Wheras, Charlotte runs half the distance, then walks another half.
If they were to compete, who wins.

Remember Speed Distance philosophy :) taught in Highschhol
Hint there will be two times when once Silvia wins and after sometime Charlotte wins. Find when and how.

But just for your start I give you a simple resolution, that may help you win an interview at most places. Though the answer is not perfect in itself. Still :)
If Charlotte runs half the distance and walks the second half, her second part will take longer. Since Silvia is running half the time, she will always run a further distance than Charlotte before he starts walking. Since they walk the same speed, Charlotte will not be able to catch her.

Determine or find duplicates in an Array

Given an array of length N containing integers between 1 and N, determine if it contains any duplicates.
Obviously I have posted a solution in an earlier post. Search that in this website.
But the point is "Is there an O(n) time solution that uses only O(1) extra space and does not destroy the original array?"
For answer email me.
My email Id. Huh!! If you can't find from this website, you are not understanding that you are not solving a simple puzzle of finding an email id. Cumon now, find that!!

Xalloc Vs Yalloc - if X='m' & Y='c'

There can be an interviewer who can throw you a question like:
Xalloc Vs Yalloc - if X='m' & Y='c'

i.e Differentiate between both

Now this is a question to test your logical and programming knowledge at once.
PS: If X=m and Y=c, the question is simply to tell difference between malloc and calloc

And hence, the answer is--

1. calloc() zero-initializes the buffer, while malloc() leaves the memory uninitialized.

2. The first letter. The number of arugments each takes. Also, calloc zero-values all elements it allocates. 


void *malloc(size_t size); 

The function allocates an object of size_t size (size_t = int, char, float...etc), and returns the address of the object if successful; otherwise, it returns a null pointer. The values stored in the object are indeterminate. You can safely convert the return value to an object pointer of any type whose size is not greater than size.

void *calloc(size_t nelem, size_t size); 

The function allocates an array object containing nelem (number of elements) each of size_t size, stores zeros in all bytes of the array, and returns the address of the first element of the array if successful; otherwise, it returns a null pointer. You can safely convert the return value to an object pointer of any type whose size in bytes is not greater than size.

Read more on Internet if you like

Program to remove duplicates in sorted array

This has been asked multiple times at multiple places. In fact, it is one of the Puzzle I had seen at Amazon Interview 2010

Write a program / algorithm to remove duplicates from a sorted array.


PS: You can devise other means. In case, you find your answer to be more efficient, let the community know about that. After posting here , you can personally email me at Toughjamy@Yahoo.com for review.

int remove_duplicates_in_Sorted_Array(int * p, int size)
int c, i = 1;
for (c=1; c < size; c++)
if (p[c] != p[i-1])
p[i] = p[c];
c++; i++;
else {c++;}
return i;}

Dog At Same Position : Bear Color Puzzle

Classic Puzzle

If a Dog walks one mile south, 
turns left and walks one mile to the east 
and then turns left again and walks one mile north 
And arrives at its original positio.

A. How is it possible
B. If it was not a Dog, but a Bear born and brought up tat the same place, what is the color of the bear.


One Possible point can be exact geographical North Pole
And if it is a bear, it is a polar bear.
So most probably White in Color!!

Important:  In addition to the trivial north pole and circle near north pole solutions, there is an additional circle near south pole solution. Set your mind juices flowing. You will get that answer too!!

Monday, March 11, 2013

Facebook Prime Bits Programming Puzzle

We know that, Every Positive integer can be represented using binary. That is, a number can be written in base of 2 also. Like decimal numbers, which is based around powers of ten. For example, 215 is really 2*102 + 1*101 + 5*100. Binary numbers  involves using 2's rather than 10's as place values, so, e.g., 5 is written as 101 = 1*22 + 0*21 + 1*20.

Every integer therefore can be respresented as a string of zeroes and ones. Define P(x) to be true if the number of ones in the binary representation of x is prime and false otherwise. 

So, e.g., P(5) is true but P(4) is false. 

Our job is to implement the function uint64_t prime_bits(uint64_t a, uint64_t b); which returns the number of integers k, a = k = b such that P(k) is true. uint64_t is a way of designating 64-bit numbers in C/C++.

This has been asked in Facebook. And people wanting to get the solution can email me at Toughjamy@yahoo.com. I do not guarantee to reply to all the emails at once, but will cater to your requests in a batch that I look once every fortnight.


Best is to discuss here..

Basic Combination Problem 1: Cards

You have a pack of 52 cards:-

1. In how many ways you can take four cards so that 2 of them are Aces and all four of them are Red
2. What is the probabilty that atleast three of them are less than 10

They are easy ones, if you have sound mathematics background. But extremely tough if you have maths phobia. Now prove what you are.

Give your answers in following format:
45 because this this this...
2/34 because blah blah blah...

Let me see how well do you sound.

Basic Combination Problem 1: Sock Pairs

If you have three pairs of socks, two pairs of pants, and four shirts, how many outfits can you wear?

Lets see how many can you answer this small one.