Interview Puzzles with answers.

How to interview a person - An Article

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<u><b><span style="font-size: large;">How to Conduct an Interview</span></b></u></div>
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Interviews have four stages that precede the writing of a story: </div>
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<li><a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html#a1">Arrangements.</a></li>
<li><a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html#a2">Preparation.</a></li>
<li><a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html#a3">The actual interview.</a></li>
<li><a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html#a4">The reconstruction.</a></li>
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<a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html" name="a1">ARRANGEMENTS</a> <br />
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               Once an interviewer has decided to interview someone, He should call the candidate in advance to make an appointment.  Identify himself by his name and the name of his publication.  If the interviewer feels that he need to do so or asked to describe what the story is about, be brief and general.  The shape of the story might change as him continue his reporting. If the interviewer interviewing several persons in connection with the story, interview the principal person last, because he will be better prepared based on what the learning from the earlier interviews.<br />
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<a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html" name="a2">PREPARATION</a></div>
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            Try to prepare as much research as possible on the person in advance on topic working on. Sources might be the library, public records, the internet and the expert people in that technology for background information.  Prepare the questions in advance if necessary writing and bring them into the interview.  Refer to them but don't show them to the candidate, because it creates too formal an atmosphere.  Ask other questions as they might arise, based on what the candidate says or something new that might come at the moment.  Bring pencil (or pen) and paper.  A stenographer's notebook is usually easier to handle than a large pad but use whatever is comfortable.  Bring a tape recorder but be sure to get the permission to use it from the person you are interviewing.  <br />
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<a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html" name="a3">THE INTERVIEW </a></div>
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            It is inadvisable to launch right into the interview unless it’s being given a few minutes.  Some casual conversation to start with will relax both of you.  Interviewers should ask Questions should be as short as possible.  Give the respondent time to answer.  Interviewers must be a good listener. If candidate prattles on, it is appropriate to move on as politely.  Interviewer might say something such as:  "Fine, but let me ask you this ".  Try to draw out specifics:  How long, how many, when, etc.?  <br />
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          Try to absorb the atmospherics of the locale where the interview takes place, with particular attention to what might be a reflection of the candidate’s personality and interests, such as photos of children or bowling trophies or a paper-littered desk or a clean one, etc.  Note characteristics of the candidate that might be worth mentioning in your story, such as pacing, looking out the window to think, hand gestures and the like.  Invite the person to call you if she/he thinks of anything pertinent after the interview.  It often happens, Interviewer should provide his name, email addresses and phone number on a card or piece of paper before to leave.  If that person has a secretary, be sure to get that person's name and telephone number, too, in case there is some detail that needs follow up and, again, leave information as to how you may be contacted.  If a photo is needed and is not taken during the interview, be sure to make arrangements then to have one taken at a later time.<br />
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<a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html" name="a4"> RECONSTRUCTION </a></div>
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           As soon as it's practical after the interview, find a quiet place to review the handwritten notes.  While taking notes, that may have written abbreviations for words that won't mean anything in a day or two later.  Or some scribbling may need deciphering, and, again, it is more likely to be better able to understand the scribbles soon after the interview.  Underline or put stars alongside quotes that seemed most compelling. One star for a good quote, two stars for a very good one, etc.   It will speed the process when you get to the writing stage.  One other thing to look for in the notes:  the quote wrote down might not make a lot of sense, unless to remember what specific question it was responding to.  In short, fill in whatever gaps exist in the notes that will help better understand them when writing.</div>
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<u><span style="font-size: large;"><b>How to Interview a Programmer</b></span></u></div>
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<i><b>Finding good programmers is hard because good programming is dependent on much more than just knowledge of programming language syntax. </b></i></div>
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         1.  The Interviewer needs someone who, despite wearing striped pants with a polka dot shirt, has a good sense of taste in OO design. <br />
        2.  He need someone who the candidate is creative enough to find innovative solutions to problems, yet anal retentive enough to always line up their curly braces. <br />
        3. The Interviewer needs someone who (the Programmer) is humble enough to be open to suggestions for improvement, but arrogant enough to stand firm and provide leadership when they are the best person to provide it.<br />
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<i><b>How to tell all this about a stranger by spending 30 minutes with them in a conference room? </b></i><br />
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<b>Summery:</b><br />
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 <a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html#b1">Explore an Area of Expertise </a><br />
 <a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html#b2">Have Them Critique Something</a><br />
 <a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html#b3">Ask Them to Solve a Problem</a><br />
 <a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html#b4">Look at Their Code</a><br />
 <a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html#b5">Ask About a People Problem</a><br />
 <a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html#b6">Get to Know Them</a><br />
 <a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html#b7">Conclusion</a><br />
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<b><a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html" name="b1">Explore an Area of Expertise</a></b><br />
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Rather than simply look for expertise and experience in the exact area in which the candidate will work, it is necessary look for general programming talent and ability. One way to explore and judge a candidate's talents is to explore an area of their expertise: <br />
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<li>Hire for talent. One of the biggest mistakes companies make is to recruit from a shopping list: I need a programmer with six years Java, three years Oracle, and two years EJBs. The world changes, so to hire folks who change with it. Look for people who know computing, not necessarily particular narrow niches. Not only will they adapt better in the future, they're also more likely to be innovative in the present.  </li>
<li> To identify how good the candidates are technically, I let them choose an area in which they feel they have expertise. I need them to know something well, and I ask them about that. I ask them why. I want them to know why something in their area of expertise works the way it does. I'm not necessarily after an expert in the area I need. If they learned why in the past, I have confidence they'll learn why in the future. </li>
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<b><a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html" name="b2">Have Them Critique Something</a></b><br />
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Another technique involves the importance of creating a dialog with the candidate. To get to know the candidate's talents and personality, Do n’t merely ask questions that have short factual answers. Find a way to engage a conversation. To stimulate dialog, ask the candidate to critique some technology: <br />
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<li>I ask candidates to critique a system or platform that we both have in common, preferably something they will use on the job. For example, I might ask, "What parts of Java don't you like and why?" </li>
<li>I give candidates samples of our current code and ask them to explain and critique it. This gives me a sense of their skills, but also lets them know what they can expect. </li>
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<b><a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html" name="b3">Ask Them to Solve a Problem</a></b><br />
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Another way to foster an open-ended dialog is to ask the candidate to perform a task: to solve a problem or create a design. Although everyone at the meeting seemed to agree that this was important and useful technique, it also generated a lot of concern. People felt that asking the candidate to solve puzzles and problems needed to be done with care:<br />
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Several expertise interview taken and their review is given below<br />
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<li>I like to ask a candidate to solve a small-scale design problem, finger exercises, to see how they think and what their process is: "How would you write a function that tells me if its argument is a power of 2?" I'm not looking for the optimal bit-twiddling solution ((n & -n) == n). I'm looking to see if they get the method signature right, if they think about boundary cases, if their algorithm is reasonable and they can explain its workings, and if they can improve on their first attempt. </li>
<li>I ask candidates to create an object model of a chicken. This eliminates any problems with uncertainties about the problem domain, because everyone knows what a chicken is. I think it also jars people away from the technical details of a computer. It tests to see if they are capable of thinking about the big picture. </li>
<li>I hate anything that asks me to design on the spot. That's asking to demonstrate a skill rarely required on the job in a high-stress environment, where it is difficult for a candidate to accurately prove their abilities. I think it's fundamentally an unfair thing to request of a candidate. </li>
<li>I don't like when I'm asked to write a program that does X on a piece of paper. Don't ask the candidate to write a program on paper. That is a waste of time and sweat. People don't write software on paper, they do it with computers using auto-completion, macros, indexed API documentation, and context-sensitive help. They think about it, refractor it, and even rewrite it. If you want to see a person's work, ask them to write some small module or implement some interface before the interview and bring the code on a notebook PC or on hard copy. Then you can review it and discuss the design, coding style, and decisions that went into it. This will give you a much more realistic and useful assessment of a person's work and style. </li>
<li>I like design dialog questions that don't have a single fixed answer. That way they have to ask me questions, and this sparks a discussion. It's good to have a whiteboard available in the room. A dialog lets the interviewer see how the interviewee works, whereas a question of fact is just that: it is great for TV quiz shows, but doesn't tell you how someone will work and approach things over time. A puzzle question requires knowing a trick, which is in essence something that is either known or unknown. I dislike puzzle questions, because they don't require dialog. </li>
<li>What constitutes a reasonable question depends a lot on the candidate's experience and maturity. </li>
<li>I look for people with curiosity. Present problems, not puzzles. </li>
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<b><a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html" name="b4">Look at Their Code</a></b><br />
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          One technique we all seemed to like: Have the candidate bring a code portfolio to the interview. Look at the candidate's code and talk to them about it. Although we were concerned that some candidates may not have code they could legally bring to the interview, we figured most candidates could probably come up with something. It can't hurt at least to ask a candidate to bring to the interview a sample of code they had written in the past. <br />
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         Find Out What Books They Read Several people indicated that they ask candidates about the programming books they read to see if a programmer is self-motivated or concerned about improving their own programming skills:<br />
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<b><a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html" name="b5">Ask About a People Problem</a></b><br />
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            As important as technical ability, or perhaps more important, is personality. How well would the candidate fit the team? How well would they fit the work environment? People used various techniques to judge personality. Good citizenship is probably more important than technical prowess, because if you have people with the right kind of attitude and demeanor, you can help them gain the technical knowledge and software development habits. But if you have people who lack humility and maturity, it can be extremely difficult to get them to cooperate in reaching a goal, no matter how bright they are or what they've accomplished in the past. <br />
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<b><a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html" name="b6">Get to Know Them</a></b><br />
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          Perhaps the prominent theme of our discussion was that you need to try to get to know the candidate as best you can. Talk to the candidate in the interview. Try to get a feel for them. If possible, bring them in on a trial basis or for a probationary period. That would give you more time to get to know the candidate, and give the candidate more time to get to know you:<br />
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<i>Chuck Allison:</i> I talk to them. I get a feel for them. I always ask about what they've done. I have found that by discovering what a person is excited about technically, you can learn a lot of important things about them. In the past I've asked people to describe a project that was especially interesting to them, or that was challenging and successful. On occasion I've asked what they've done that they're the most proud of. This usually reveals the depth of one's understanding and mastery. It also gets them to turn on the fire hose verbally, and you can sit back and get most of the answers you need.<br />
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<i>Randy Stafford: </i>I look at past projects listed on their resume, and ask them to talk about those projects—how was the team organized, what the technologies and architectures were used, was the software successful in production, etc. In their answers I'm listening for what lessons they learned from those experiences, and whether those lessons match with lessons I've learned from my experiences and from professional literature. I get a glimpse into how they perceive themselves in relation to the world around them. Some come off as arrogant, some ignorant, some helpless. Others sound humble, intelligent, and motivated. I often ask them what software development literature they read. Continuous education is very important to me.<br />
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<i>Angelika Langer: </i>In Germany, hiring is like marrying someone. It's "until death do us part"—a marriage without the backdoor of a divorce, because you can't fire employees. The only chance for firing someone is during a three- to six-month probationary period, or when the company goes out of business. The major filtering is done before the interview, based on the curriculum vitae (CV) and submitted papers, such as evaluations from former employers. (In Germany, employers must provide every employee with a written evaluation when they leave the company.) The interview itself is usually brief. The main tool in filtering is scrutinizing the CV and papers; 98 percent of all applicants are disqualified in this phase. The interview should confirm the impression you gain from the applicant's papers and allows you to sense their personality. The lucky winner then goes on a probationary period. Probation definitely does not replace the filtering; it just keeps a last exit open until you really must commit.<br />
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<i>Andy Hunt: </i>We've hired people who interviewed well, but they were terrible at the job. If possible, hire them in for a trial period.<br />
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<i>Dawn McGee: </i>You could also bring candidates in for half a day, and have them do what they would be doing on the job.<br />
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<b><a href="http://interviewpuzzle.blogspot.com/2010/08/how-to-conduct-interview.html" name="b7">Conclusion</a></b><br />
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             To sum up the overlying themes from our hour-long discussion in Portland: You should look for talent and fit more than specific skill sets. Ask open-ended questions to initiate revealing dialog. Ask candidates to critique something. Ask them to design something. Investigate their past experience. Review their code. And through conversation and, if possible, a trial period, you should try to become familiar with the candidate's technical abilities, talents, and personality. <br />
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How to interview a person - An Article

How to Conduct an Interview Interviews have four stages that precede the writing of a story: Arrangements. Preparation. ...

Poisened Drink Puzzle

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<a class="thickbox" href="http://3.bp.blogspot.com/_pxUNdWyjHeo/TH3a2xU8yxI/AAAAAAAAAKw/1gQA-uXjbOg/s1600/scotch.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Poisened Drink" border="0" height="320" src="http://3.bp.blogspot.com/_pxUNdWyjHeo/TH3a2xU8yxI/AAAAAAAAAKw/1gQA-uXjbOg/s320/scotch.jpeg" title="Poisened Drink" width="239" /></a></div>
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<b>Poisened Drink Puzzle</b></div>
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                     A rich old man has died. After his  death, his children are surprised to learn that he has left all of his  money to his oldest son Jeremiah, who loved him dearly, and ignored his  other children, who hated him. </div>
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                  So,  the funeral is a day or two later, and the other sons and daughters  have decided to kill Jeremiah and take his inheritance. Since his  father's death, Jeremiah has taken to drinking, and they know that, at  the wake, he's going to be gulping down the liquor like it was nectar of  the gods. So they decide to poison the drinks. One of the other sons,  Wallace, tends bar, and gets the poison all ready. So  Jeremiah comes up, crying and depressed, and orders a scotch on the  rocks. Wallace serves him one, and he chugs it down in two seconds.  "Give me another." Wallace gives him a second glass of scotch, which he  also drinks in a matter of moments. The other siblings are puzzled...the  poison is fast-acting; Jeremiah should be convulsing on the floor and  retching his guts out. Finally, fifteen minutes later, a rather  inebriated and very much alive Jeremiah orders one last glass of scotch,  but as Wallace hands it to him, he changes his mind and leaves,  sobbing. The other siblings come over to Wallace, and wonder what's  going on. They talk about what could have gone wrong for a few minutes,  and figure the poison's harmless. So Wallace sips the drink he poured  for Jeremiah, and is pronounced DOA thirty minutes later. </div>
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Why did Jeremiah live? (He had no immunity to the poison, he didn't know it was coming, and the poison was obviously deadly.)<br />
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          <span style="font-size: small;">Jeremiah orders a scotch on the rocks (ice  cubes). Dropping the poison into his drink, it lands on top of the ice  cubes. Jeremiah downs his two drinks very quickly, not giving enough  time for the poison to mix with his drink. Conversely, the brother waits  a "few minutes" before drinking, allowing the ice cubes to melt and  giving ample time for the poison to mix with the scotch. He is soon dead  as a result!  </span></div>

Poisened Drink Puzzle

Poisened Drink Puzzle A rich old man has died. After his death, his children are surprised to learn tha...

Four ships Puzzle

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<a class="thickbox" href="http://3.bp.blogspot.com/_pxUNdWyjHeo/THnmYAGvD-I/AAAAAAAAAKI/J_zAbRvw3mU/s1600/DCL4ShipsSmaller.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="four ships" border="0" src="http://3.bp.blogspot.com/_pxUNdWyjHeo/THnmYAGvD-I/AAAAAAAAAKI/J_zAbRvw3mU/s320/DCL4ShipsSmaller.jpg" title="four ships" /></a></div>
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<span style="font-size: large;"><b>Puzzle :</b></span><br />
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Four ships are sailing on a 2D planet in four different directions. Each ships traverses a straight line at constant speed. No two ships are traveling parallel to each other. Their journeys started at some time in the distant past. Sometimes, a pair of ships collides. A ship continues its journey even after a collision. However, it is strong enough only to survive two collisions; it dies when it collides a third time. The situation is grim. Five of six possible collisions have already taken place (no collision involved more than 2 ships) and two ships are out of commission. What fate awaits the remaining two?</div>
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Let z-axis denote time. let x- and y- axes denote the 2D planet. Then the four trajectories are straight lines. Since no collision involved more than two ships, these four lines must all lie in a plane. So, one might be tempted to believe that the two other ships will also collide. But, they might have collided in negative time. So, it cannot be decided from the given information that the two ships will collide or not?<br />
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This can be made clearer through the following two diagrams. In the first one, the four ships move such that there is no collision between the two ships. In the other diagram, the four ships move such that there is a collision between them.</div>

Four ships Puzzle

Puzzle : Four ships are sailing on a 2D planet in four different directions. Each ships traverses a straight line at constant speed. N...

Three Boxes and a Ruby Puzzle with Solution

Three Boxes and a Ruby Puzzle with Solution

Puzzle : Alice places three identical boxes on a table. She has concealed a precious ruby in one of them. The other tw...

Eight Queens Puzzle

<div style="text-align: center;"><u><span style="font-size: large;"><b>Eight Queens Puzzle</b></span></u></div><div style="text-align: justify;"><br />
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</div><div style="text-align: justify;">The eight queens puzzle is the problem of placing eight chess queens  on an 8×8 chessboard such that none of them are able to capture any other using the standard chess queen's moves. </div><div style="text-align: justify;"><br />
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 Available movement of the Queen is shown in above picture. The queens must be placed in such a way that no two queens attack each other. In chess, a queen can move as far as horizontally, vertically, or diagonally. The standard 8 by 8 Queen's problem asks how to place 8 queens on an ordinary chess board so that none of them can hit any other in one move.<br />
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<embed bgcolor="#000000" height="510" pluginspage="http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash" quality="high" src="http://tszone.co.cc/8Queens.swf" type="application/x-shockwave-flash" width="760"></embed><br />
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This puzzle has <u><b>twelve unique solution</b></u>. The following image show one solution as using backtracking algorithm method. See <a href="http://en.wikipedia.org/wiki/Eight_queens_puzzle">wikipedia </a>for more details about 8 Queen puzzle.<br />
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<u><span style="font-size: large;"><b>Algorithms :</b></span></u><br />
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Check the following links <br />
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1. <a href="http://www.mactech.com/articles/mactech/Vol.13/13.12/TheEightQueensProblem/%20">http://www.mactech.com/articles/mactech/Vol.13/13.12/TheEightQueensProblem/ </a><br />
2. <a href="http://yuval.bar-or.org/index.php?item=9">http://yuval.bar-or.org/index.php?item=9</a><br />
3. <a href="http://firefang.net/english/n-queens">http://firefang.net/english/n-queens</a><br />
4. <a href="http://bridges.canterbury.ac.nz/features/eight.html">http://bridges.canterbury.ac.nz/features/eight.html</a><br />
5. <a href="http://mathworld.wolfram.com/QueensProblem.html">http://mathworld.wolfram.com/QueensProblem.html</a><br />
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for algorithm to solve this problem.<br />
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<u><span style="font-size: large;"><b>Source Code :</b></span></u><br />
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The solved java program is available here.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">1. <a href="http://tszone.co.cc/NQueens.java">http://tszone.co.cc/NQueens.java</a></div><div style="text-align: justify;">2. <a href="http://rooparam.blogspot.com/2009/12/eight-queens-solution-with-dfs-using.html">http://rooparam.blogspot.com/2009/12/eight-queens-solution-with-dfs-using.html</a></div>

Eight Queens Puzzle

Eight Queens Puzzle The eight queens puzzle is the problem of placing eight chess queens on an 8×8 chessboard such that none of them are ...

Hats and IIT students

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<span style="font-size: large;"><b>Puzzle:</b></span></div>
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This is another hats puzzle same like as <a href="http://interviewpuzzle.blogspot.com/2010/05/prisoners-and-hats-puzzle.html">prisoners and hats puzzle</a>. The puzzle is Nine IIT students were sitting in a classroom. Their professor wanted them to test. Next day the professor told all of his 9 students that he has 9 hats, The hats either red or black color. He also added that he has at least one hat with red color and the no. of black hats is greater than the no. of red hats. The professor keeps those hats on their heads and ask them tell me how many red and black hats the professor have? Obviously students can not talk to each other or no written communication, or looking into each other eyes; no such stupid options and no tricks.</div>
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Professor goes out and comes back after 20 minutes but nobody was able to answer the question. So he gave them 10 more minuets but the result was the same. So he decides to give them final 5 minutes. When he comes everybody was able to answer him correctly.</div>
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So what is the answer? and why? </div>
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<b><span style="font-size: large;">Answer :</span></b></div>
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After 20 minutes :<br />
Lets assume that their is 1 hat of red color and 8 hats of black color.  The student with red hat on his head can see all 8 black hats, so he  knows that he must be wearing a red hat.<br />
Now we know that after first interval nobody was able to answer the prof that means our assumption is wrong. So there can not be 1 red and 8 black hats.<br />
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After second interval of 10 minutes :<br />
Assume that their are 2 hats of red color and 7 hats of black color. The  students with red hat on their head can see all 7 black hats and 1 red  hat, so they know that they must be wearing a red hat.<br />
Now we know that after second interval nobody was able to answer the prof that means our assumption is again wrong. So there can not be 2 red and 7 black hats.</div>
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After third interval of final 5 minutes :<br />
Now assume that their is 3 hats of red color and 6 hats of black color.  The students with red hat on their head can see all 6 black hats and 2  red hats, so they know that they must be wearing a red hat.<br />
Now we know that this time everybody was able to answer the prof that means our assumption is right. <br />
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So there are 3 red hats and 6 black hats. <br />
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Now as everybody gave the answer so there can be a doubt that only those 3 students know about it how everybody came to know ?<br />
Then here is what i think, the professor gave them FINAL 5 minutes to  answer, so other guys will think that the professor expects the answer  after 3rd interval (according to prof it must be solved after 3  intervals), so this is the clue for others.   </div>

Hats and IIT students

Puzzle: This is another hats puzzle same like as prisoners and hats puzzle . The puzzle is Nine IIT students were sitti...

Engineers and Managers Puzzle

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<u><span style="font-size: large;">Engineers and Managers Puzzle</span></u></div>
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<span style="font-size: large;"><b>Puzzle :</b></span><br />
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         In a city, The police has surrounded the Bank. There are 50 people in the building. Each person is either an engineer or a manager of the bank. All computer files have been deleted, and all documents have been shredded by the managers. The problem confronting the police is to separate the people into these two classes, so that all the managers are locked in a room  and all the engineers are freed. every people knows the status of all others. The interrogation consists entirely of asking person i if person j is an engineer or a manager. The engineers always tell the truth. What makes it hard is that the managers may not tell the truth. In fact, the managers are evil geniuses who are conspiring to confuse the interrogators.<br />
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   1. Under the assumption that more than half of the people are engineers, can you find a strategy for the Police to find one engineer with at most 49 questions?<br />
   2. Is this possible in any number of questions if half the people are managers?<br />
   3. Once an engineer is found, he/she can classify everybody else. Is there a way to classify everybody in fewer questions?</div>
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<b><span style="font-size: large;">Answer :</span></b></div>
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Part 1: <br />
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Here's an n-1 query solution to part 1. Maintain three sets of people: UNSEEN, STACK, and DISCARD. Initialize the process by picking one arbitrarily to be the STACK, everything else is UNSEEN. Repeat the following step until UNSEEN is empty:<br />
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    Pick an UNSEEN element x, remove it from UNSEEN. Ask the top of the STACK y about x. If y says "manager" pop y off the stack and DISCARD both x and y. If it says "engineer" add x to the top of the STACK.<br />
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After all elements have been processed in this way (n-1 comparisons), the top of the stack must be an engineer.<br />
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Why does this work? First observe that whenever we discard a pair, at least one of them is a manager. So among the rest of them (STACK and UNSEEN) a majority must still be engineers. So at the end, when UNSEEN is empty, there must be an engineer in the stack, therefore the top of the stack must be an engineer.<br />
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This can be improved to 48 simply by stopping one earlier. When there's one UNSEEN left, if the stack is empty, that UNSEEN one is an engineer. Otherwise, the top of the stack must be an engineer.<br />
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first step we can just throw out one person, and appy this algorithm to the remaining 49 obtaining 47 comparisons. This gives the optimal algorithm.<br />
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This is optimal. The proof appears in the solution of homework assignment 7 of Steven Rudich's course 15-251 taught at CMU in the spring semester of 2002. See Solution 7.<br />
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Part 2: If half or more of the people are managers, then the problem cannot be solved. The managers can ensure this simply by always lying. Now there's way to separate the two sets of people. Each one simply claims the others are Managers.<br />
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Part 3: I don't know any better solution than to simply using the solution to Part 1 to identify everybody.<br />
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Engineers and Managers Puzzle

Engineers and Managers Puzzle Puzzle : In a city, The police has surrounded the Bank. There are 50 people in the buildin...

Lateral Thinking Puzzles

<div style="text-align: justify;">Puzzle 1:</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">A man is trapped in a room. The room has only two possible exits: two doors. Through the first door there is a room constructed from magnifying glass. The blazing hot sun instantly fries anything or anyone that enters. Through the second door there is a fire-breathing dragon. How does the man escape?</div><div style="text-align: justify;"><br />
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</div><div style="text-align: justify;">He waits until night time and goes out the first door.</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">Puzzle 2:</div><div style="text-align: justify;"><br />
</div><div style="text-align: justify;">In a far away land, it was known that if you drank poison, the only way to save yourself is to drink a stronger poison, which neutralizes the weaker poison. The king that ruled the land wanted to make sure that he possessed the strongest poison in the kingdom, in order to ensure his survival, in any situation. So the king called the kingdom's pharmacist and the kingdom's treasurer, he gave each a week to make the strongest poison. Then, each would drink the other one's poison, then his own, and the one that will survive, will be the one that had the stronger poison.<br />
The pharmacist went straight to work, but the treasurer knew he had no chance, for the pharmacist was much more experienced in this field, so instead, he made up a plan to survive and make sure the pharmacist dies. On the last day the pharmacist suddenly realized that the treasurer would know he had no chance, so he must have a plan. After a little thought, the pharmacist realized what the treasurer's plan must be, and he concocted a counter plan, to make sure he survives and the treasurer dies. When the time came, the king summoned both of them. They drank the poisons as planned, and the treasurer died, the pharmacist survived, and the king didn't get what he wanted.<br />
What exactly happened there?</div><div style="text-align: justify;"><br />
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</div><div style="text-align: justify;">The treasurer's plan was to drink a weak poison prior to the meeting with the king, and then he would drink the pharmacist's strong poison, which would neutralize the weak poison. As his own poison he would bring water, which will have no effect on him, but the pharmacist who would drink the water, and then his poison would surely die. When the pharmacist figured out this plan, he decided to bring water as well. So the treasurer who drank poison earlier, drank the pharmacist's water, then his own water, and died of the poison he drank before. The pharmacist would drink only water, so nothing will happen to him. And because both of them brought the king water, he didn't get a strong poison like he wanted.</div>

Lateral Thinking Puzzles

Puzzle 1: A man is trapped in a room. The room has only two possible exits: two doors. Through the first door there is a room constructed f...

The Gold Chain -Interview Puzzle

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<span style="font-size: large;"><b><span style="font-family: Courier New,Courier;">The Gold Chain - Puzzle :</span></b></span><br />
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<b><span style="font-family: Courier New,Courier;">         </span></b><span style="font-family: Courier New,Courier;">A woman wants to buy a painting at an auction where you bid grams of gold instead of money.  She owns a gold chain made of 23 interlocking loops, each weighing 1 gram.  She wants to go to a jeweler before the auction to cut the minimum number of loops that would allow her to pay any sum from 1 to 23.  For example, she could pay a 13 gram price with a 12 link chain and a single link.  After much thought, she figures out a way to do it by cutting just 2 of the loops in the chain.  How many loops are in the pieces of chains that she has after the 2 cuts?</span></div>
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Make a cut in 4 th and loops of the Gold chain so you can get pieces of 1,1,3,6 and 12. from this you can weights from 1 to 23 grams.</div>
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The Gold Chain -Interview Puzzle

The Gold Chain - Puzzle : A woman wants to buy a painting at an auction where you bid grams of gold instead of money. ...

Dragon and Knight - Trilogy interview puzzle

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<span style="font-size: large;"><b>Dragon and Knight - Trilogy interview puzzle</b></span><br />
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       This is another one famous puzzle asked in many interview puzzle. This was asked in Trilogy interview. </div>
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Lets consider a dragon and knight live on an island. That island has seven poisoned  wells, which is numbered 1 to 7. If you drink from a well, you can only save  yourself by drinking from a higher numbered well. The Well whose is number 7 is located at  the top of a high that mountain, so only the dragon can reach it.<br />
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One day they decide that the island isn't big enough for the two of  them, and they have a duel. Each of them brings a glass of water to the  duel, they exchange glasses, and drink. After the duel, the knight lives  and the dragon dies.<br />
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Why did the knight live? Why did the dragon die?</div>
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              Dragon knows that knight cant reach well 7. So he thinks that if i give  knight water from well 6 or 7, knight would die for sure. So he would  get water from well 6 or 7 for knight.<br />
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Knight knew that no matter from which well he gives the water, dragon  will go and drink from well 7 and live. So he got normal water for  dragon and before duel drank water from well 1. <br />
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When they exchanged glasses and drank water, dragon rushed to well 7 and  drank poison from it, thinking that it would cure the poison he just  drank (but he drank normal water), so dragon died. Knight on the other  hand already had poison from well 1 so what dragon gave him effectively  cured him. So he lived.</div>
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comments if you have any other answers..</div>
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Dragon and Knight - Trilogy interview puzzle

Dragon and Knight - Trilogy interview puzzle This is another one famous puzzle asked in many interview puzzle. This was asked i...

Blue-eyed Samurais Puzzle

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           A remote island contains a tribe whose members have either blue or brown eyes. Tribe members do not know the color of their eyes and if they learn it, they must kill themselves the same night. Every member of the tribe always behaves logically. So one day, a sailor visits the island and makes an observation that at least one of the members of the tribe has blue eyes. On the 10th night after that, all people with blue eyes kill themselves. How many blue-eyed people were there in the tribe?</div>
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           Ten. The logic goes as follows. If there were only one person with blue eyes on the island, then he would see that no one else has blue eyes and will kill himself on the first night. If there were two people with blue eyes, then one of the people with blue eyes would see that the second blue-eyed person did not kill himself on the first night, leading him to conclude that since he sees no one else with blue eyes, he must be one of them and will kill himself on the second night. The other blue-eyed person will follow the same logic and also kill himself on the second night. The same idea applies to the rest of the problem.</div>
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Comments if you have any other answers </div>

Blue-eyed Samurais Puzzle

Puzzle : A remote island contains a tribe whose members have either blue or brown eyes. Tribe members do not know the c...

Image Puzzles with Answers

Puzzle Images<br />
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Image Puzzles with Answers

Puzzle Images 1. 2. 3. 4. 5.

Infosys Interview puzzles with answers

<div style="text-align: center;"><span style="font-size: large;"><b>Logical Puzzles </b></span></div><div style="text-align: center;"><br />
</div><div style="text-align: justify;">1.  A clock with the hours round the face in Roman block numbers, as illustrated in the sketch fell down and the dial broke into four parts. The numerals in each part in every case summed to a total of 20. Can you show how the four parts of the clock face was broken?<br />
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2. Shown in the sketch are 6 matches. Can you rearrange them to make nothing? <br />
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3.  Here is a sketch: Can you rearrange the position of the numbers 1 to 10 so that the sum of any two adjacent numbers is equal to the sum of the pair of numbers at the opposite ends of the diameter?<br />
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4. Can you place 10 coins in such a way that they lie in 5 straight lines and on each line there are 4 coins. There are at least two solutions.<br />
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</div>5. Nine dots are arranged by 3 rows of 3 in the form of a square as shown in the sketch below:<br />
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Can you draw 4 straight lines, the second beginning where the first ends, the third beginning where the second ends and the fourth beginning where the third ends so that each dot is or at least one line?<br />
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<div style="text-align: center;"><span style="font-size: large;"><b>Answers</b></span></div><div style="text-align: center;"><br />
</div><div style="text-align: left;">1.   <span id="goog_697837821"></span><span id="goog_697837822"></span></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="http://2.bp.blogspot.com/_pxUNdWyjHeo/TFxObcjm9QI/AAAAAAAAAHI/hbfGtP_Qf_w/s1600/11.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/_pxUNdWyjHeo/TFxObcjm9QI/AAAAAAAAAHI/hbfGtP_Qf_w/s320/11.PNG" /></a></div><div style="text-align: left;"><br />
</div><div style="text-align: left;">2.</div><div class="separator" style="clear: both; text-align: center;"><a href="http://1.bp.blogspot.com/_pxUNdWyjHeo/TFxOcFyilrI/AAAAAAAAAHQ/bEbXvBkf1Bw/s1600/21.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://1.bp.blogspot.com/_pxUNdWyjHeo/TFxOcFyilrI/AAAAAAAAAHQ/bEbXvBkf1Bw/s320/21.PNG" /></a></div><div style="text-align: left;"><br />
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</div><div style="text-align: left;">3.</div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="http://3.bp.blogspot.com/_pxUNdWyjHeo/TFxOc3rFx2I/AAAAAAAAAHY/Vvb-LE3NNL8/s1600/31.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://3.bp.blogspot.com/_pxUNdWyjHeo/TFxOc3rFx2I/AAAAAAAAAHY/Vvb-LE3NNL8/s320/31.PNG" /></a></div><div style="text-align: left;"><br />
</div><div style="text-align: left;">4.</div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="http://3.bp.blogspot.com/_pxUNdWyjHeo/TFxOd2MFGoI/AAAAAAAAAHg/VWcWRnseJ0Y/s1600/41.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://3.bp.blogspot.com/_pxUNdWyjHeo/TFxOd2MFGoI/AAAAAAAAAHg/VWcWRnseJ0Y/s320/41.PNG" /></a></div><div style="text-align: left;">5.</div><div class="separator" style="clear: both; text-align: center;"><a href="http://3.bp.blogspot.com/_pxUNdWyjHeo/TFxOeaLLs_I/AAAAAAAAAHo/XfvCdtARLek/s1600/51.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://3.bp.blogspot.com/_pxUNdWyjHeo/TFxOeaLLs_I/AAAAAAAAAHo/XfvCdtARLek/s320/51.PNG" /></a></div><div style="text-align: left;"><br />
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Infosys Interview puzzles with answers

Logical Puzzles 1. A clock with the hours round the face in Roman block numbers, as illustrated in the sketch fell down and the dial broke...