Sunday, August 18, 2013

Top 10 Interview Puzzles You Should Be Prepared For

Y.Narayana Reddy | 
Puzzles, riddles, logical questions, and lateral thinking questions are important part of any selection process for a job interview. Every eligible candidate is first asked to clear the aptitude round and only then the whole interview process puzzlesbegins. These tests are the most objective way of screening a candidate; there is no subjectivity involved at all – either your answers are right or they are wrong. So your future may depend on your ability to pass them. So being good at solving puzzles can you an edge and make the whole hiring process easier. You can check how good you are by answering these top 10 interview puzzles (Don’t google them, try solving and wait for the next blog for answers):
1. The Two Egg Problem
You are given two eggs, and access to a 100-storey building. Both eggs are identical. The aim is to find out the highest floor from which an egg will not break when dropped out of a window from that floor. If an egg is dropped and does not break, it is undamaged and can be dropped again. However, once an egg is broken, that’s it for that egg. If an egg breaks when dropped from floor n, then it would also have broken from any floor above that. If an egg survives a fall, then it will survive any fall shorter than that.
The question is: What strategy should you adopt to minimize the number egg drops it takes to find the solution?.
2. Heaven’s Gate Problem
A person dies, and arrives at the gate to heaven. there are three doors. one of them leads to heaven. another one leads to a 1-day stay at hell, and then back to the gate, and the other leads to a 2-day stay at hell, and then back to the gate. every time the person is back at the gate, the three doors are reshuffled. How long will it take the person to reach heaven?
3.  Jelly Bean Problem
You have three jars that are all mislabeled. one contains peanut butter jelly beans, another grape jelly jelly beans, and the third has a mix of both (not necessarily a 50/50 mix). How many jelly beans would you have to pull out, and out of which jars, to find out how to fix the labels on the jars?
4.  King and Wine
A bad king has a cellar of 1000 bottles of delightful and very expensive wine. A neighboring queen plots to kill the bad king and sends a servant to poison the wine. Fortunately (or say unfortunately) the bad king’s guards catch the servant after he has only poisoned one bottle. Alas, the guards don’t know which bottle but know that the poison is so strong that even if diluted 100,000 times it would still kill the king. Furthermore, it takes one month to have an effect. The bad king decides he will get some of the prisoners in his vast dungeons to drink the wine. Being a clever bad king he knows he needs to murder no more than 10 prisoners – believing he can fob off such a low death rate – and will still be able to drink the rest of the wine (999 bottles) at his anniversary party in 5 weeks time. Explain what is in mind of the king, how will he be able to do so ? (of course he has less then 1000 prisoners in his prisons)
5. Four Ships Puzzle
Four ships are sailing 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. Now, 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?
6. How to Escape?
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?
7.  Truthtown or Liartown?
You’re trying to get to Truthtown. You come to a fork in the road. One road leads to Truthtown (where everyone tells the truth), the other to Liartown (where everyone lies). At the fork in the road is a man from one of those towns — but which one? You get to ask him one question to discover the way. What’s the question?
8.  Age of the Children
A man walks into a bar, orders a drink, and starts chatting with the bartender. After a while, he learns that the bartender has three children. “How old are your children?” he asks. “Well,” replies the bartender, “the product of their ages is 72.” The man thinks for a moment and then says, “that’s not enough information.” “All right,” continues the bartender, “if you go outside and look at the building number posted over the door to the bar, you’ll see the sum of the ages.” The man steps outside, and after a few moments he reenters and declares, “Still not enough!” The bartender smiles and says, “My youngest just loves strawberry ice cream.” How old are the children? A variant of the problem is for the sum of the ages to be 13 and the product of the ages to be the number posted over the door. In this case, it is the oldest that loves ice cream. Then how old are they?
9.  3 light switches 
You have a set of 3 light switches outside a closed door. One of them controls the light inside the room. With the door closed from outside the room, you can turn the light switches on or off as many times as you would like. You can go into the room – one time only – to see the light. You cannot see the whether the light is on or off from outside the room, nor can you change the light switches while inside the room. No one else is in the room to help you. The room has no windows.
Based on the information above, how would you determine which of the three light switches controls the light inside the room?
10. Chasing Dog
There are four dogs each at the corner of a unit square. Each of the dogs starts chasing the dog in the clockwise direction. They all run at the same speed and continuously change their direction accordingly so that they are always heading straight towards the other dog. How long does it take for the dogs to catch each other and where?

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