How to measure time Candle Puzzles in Interviews

Sunday, 4 May 2014

Candles puzzles is common today in different interviews. Basically we measure given time with 1 or 2 candles. Suppose 1 candles burn in 1 hour. We have 2 candles find out 45 mins with these candles.


How to solve ?
Very simple don't miss these kind of puzzles. Think out of the box and give answer. Above question is very simple.

1 candle fully burns at 1 hour. Now what ?

Lighten first candle from both ends and second candle from just one end. After sometime when first candle burns completely then burn second candle from second end. Thats it.

-> When Burns with Both ends it takes 30mins
-> When Burns from 1 end it takes 1 hour.

-> After burning First candle we had already measured 30mins. Now after burning from second end. We have 30 mins to cross. So it will eventually took 15 mins.

At Last we got 30+15 mins = 45 mins.

 
-> Now measure 90 minutes from these candles ?

Lighten first candle from one side. So it will burn at 1 hour. Now lighten second candle from both ends. So it will take 30 mins. End Up time is 60mins + 30mins =90.

Think like that which comes out very handy for u.

Main thing is never give up attitude

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Mostly asked weighing balls puzzles in interview

Friday, 2 May 2014

I have faced many interviews ,got through many rounds. I m sharing my experience. Mostly in hr rounds, interviewer asks puzzles to play with student mind. I can say that clearing tech round or aptitude round is simple. Bt puzzles r very difficult to solve. Your mind doesn't perform well when someone unexpected questions. Literally, if you have some previous experience how to solve puzzles.Then it becomes easier for solving puzzles. Weighing puzzles is most likely asked in the interview.


1) we have 9 identical balls bt 1 heavy weight. We have to find that ball in minimum no. of weighing. Remember this is understandable only one pan with two halves to measure.

divide into 3 group with 3 balls each

This is basic step always divide balls in equal balls if possible. So 9balls/3=3balls (in each group)

So now put 3 balls in two pans. Suppose they r equal. Now you left with 3 balls.Put 1 ball in one side and 1 ball in other side. If they r equal. The ball which left is culprit or heavy weight ball.

Now suppose while weighing 3 balls in each side. We got one side heavy. Now take out all three balls from heavy side. Measure balls with 1 ball at each side. If we get it then it's fine otherwise left ball is heavy one.

So minimum we can get heavy weight ball in 3 trials.

 
2) Suppose we have 8 balls now find out heavy ball in those.

Now this is different case. We can't divide equal balls in groups. Firstly think before giving answer its very difficult in the beginning.

Make group like that for minimum no. of iterations.

2 group = 3 balls
1 group = 2 balls

Put 3 balls in one side and 3 balls in other. If both r equal. Then check 1 ball with other ball.


3) 12 balls in which one ball either heavy or light. You know minimum 3 iteration needed to find that ball. How could you do it?

Divide balls into 3 groups

12 balls/3 balls= 4 balls in each (maximize no. of  balls)

Weigh 2 groups 4 balls each in two sides. Now we left with 4 balls. Weight this group with any previously measured group. Then find out its complicated. I will tell you the correct solution. Before that go for the how to solve.


These r the puzzles which most likely to ask in HR interview or puzzle round. Don't think its too difficult to answer. Only need is right technique and approach.

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