You have 2 identical glass bulbs with you. Bulb
manufacturer has mentioned that each bulb might withstand a
drop of 200 Feet at maximum. Your task is to find the
height at which the bulb breaks ofcourse with minimum
number of iterations.
Assume that you have 200 blocks of 1 foot each which can be
stacked one by one to create a 200 Feet structure to carry
out the test.




Answers were Sorted based on User's Feedback



You have 2 identical glass bulbs with you. Bulb manufacturer has mentioned that each bulb might wi..

Answer / chris uzdavinis

Taking the worst case scenario, the minimum number of
iterations required is 20. Here is why:

For N drops you can cover a range of the sum(1,..N), which
is n*(n+1) / 2.

If we have 200 potential heights to test, we solve n*(n+1) =
400, and using the quadratic equation gives us
19.5062490237426, rounding up to 20.

The sequence of tests would be drop at heights of:
20
39
57
74
90
105
119
132
144
155
165
174
182
189
195
200

(Notice, the distance between each level decreases by 1 to
account for the extra drop it took to get there.)

If the bulb does not break on a level, try the next higher
number in the above sequence. If it does break, then do a
linear search starting at the previous "level", plus 1.

Any answer that partitions segments into equal lengths will
be suboptimal.

Is This Answer Correct ?    3 Yes 0 No

You have 2 identical glass bulbs with you. Bulb manufacturer has mentioned that each bulb might wi..

Answer / ram kumar.y

make the stack into 14 sections such that 10 of them will
have 14 blocks each and rest of the 4 will have 15 blocks
each.i.e., 14*10+15*4=140+60=200 blocks.
coming from the bottom keep dropping the bulb from the
highest blocks in each sections. in the worst case scenario,
the bulb may break in last(14th) section.
with the second bulb, keep dropping the bulb from any one
end of that section(in this case 14th as its the worst case)
which has 15 blocks and the first bulb has been dropped from
one of the 15 blocks. so, it takes 14 more chances(at a
worst case) to find out the block from where the bulb breaks
when dropped. So, the total no. of iterations are 14+14=28(max).

Is This Answer Correct ?    1 Yes 0 No

You have 2 identical glass bulbs with you. Bulb manufacturer has mentioned that each bulb might wi..

Answer / shantanu_sanjeev

For the best solution the worst case max drops will be "24"

For this we divide it into
1st five blocks from bottom of size 20 : 5*20 = 100
Next ten blocks of top of size 10 : 10*10 = 100

This will have a worst case at 99 when there will be 24
drops and all other numbers above 99 will have less than 24
drops.

Is This Answer Correct ?    1 Yes 0 No




You have 2 identical glass bulbs with you. Bulb manufacturer has mentioned that each bulb might wi..

Answer / magnum

in the question it is asked "THE HEIGHT AT WHICH BULB BREAKS"
not the height from which u drop so the bulb breaks.so from whatever height u may drop, the bulb if it breaks,it will break only on the ground i.e. 0 feet.

Is This Answer Correct ?    1 Yes 0 No

You have 2 identical glass bulbs with you. Bulb manufacturer has mentioned that each bulb might wi..

Answer / md

200 feet is the max height.
Means bulb can break from any feet within the max limit.

In the worst case, no of iteration will be 200.

To make situation better.. lets segmentise the 200 feet in
X segments.
Then will experiment with one bulb from top of each
segments. Bulb may break at any trial. worst case bulb
breaks at last trial. iteration = X

Now need to find the exact feet among the particular
segment. This segment has 200/X feet span.

Hence Worst case : iteration I = X + (200/X)

Now the job is to find out value of X so that I is minimum.

X=10 or X=20 in worst case min no of iteration is 30

Is This Answer Correct ?    0 Yes 0 No

You have 2 identical glass bulbs with you. Bulb manufacturer has mentioned that each bulb might wi..

Answer / nikky

question is not clear!!!

Is This Answer Correct ?    0 Yes 0 No

You have 2 identical glass bulbs with you. Bulb manufacturer has mentioned that each bulb might wi..

Answer / chris uzdavinis

Minor typo in previous answer (#7): it should say ... we
solve n*(n+1) = 200

To help get the mindset of the answer, think of the question
differently at first. Rather than solve for the fewest
number of drops to cover a range, think about a twisted
version of that question: "given a fixed number of drops,
what range can be completely covered?"

Our constraints are we have two bulbs, and we're done once
the 2nd breaks, but if it doesn't break we can use it again.

Given only 1 drop, we can only cover a range of 1. Either
it breaks or it doesn't. (If we go higher than the first
level, we don't know if it would have broken at a lower level.)

Given 2 drops, we can cover a range of 3: first drop on 2,
if it breaks, try 1, if not, try 3.

Given 3 drops, we cover a range 1..6: First drop on 3, if
it breaks, try 1, then 2. If it doesn't break, drop #2 is
on 5. If breaks, try 4. If not, try 6.

Given 4 drops, we cover a range of 1..10:
Start on 4, if breaks, try 1,2,3. If not, try 7. If
breaks, try 5,6. If not, try 9. If breaks, try 8. If not
try 10.

And so on. Thus, for N drops, we start on level N. If it
breaks, start a linear search using the remaining bulb, from
1..N-1. Thus, it took a max of 20 drops. But if it doesn't
break, we try level N+(N-1). If it breaks, start a linear
search from N+1. Otherwise try N+(N-1)+(N-2). etc.

This series is clearly the sum from 1 to N drops.

So now that we know how big of a range we can cover given a
fixed number of drops. But the original question asks us to
cover a range of 200, and find the number of drops required.
We just find the smallest integral value for N such that
sum of 1..N >= 200, which is 20.

I gave the sequence of tests in the previous post.

Is This Answer Correct ?    0 Yes 0 No

You have 2 identical glass bulbs with you. Bulb manufacturer has mentioned that each bulb might wi..

Answer / viral avalani

No. of iterations will be minimum at height of 200 ft.

Is This Answer Correct ?    0 Yes 1 No

You have 2 identical glass bulbs with you. Bulb manufacturer has mentioned that each bulb might wi..

Answer / rajendra varma

100ft

Is This Answer Correct ?    0 Yes 3 No

Post New Answer



More Puzzles Interview Questions

why do you want to work here?

1 Answers   Qatar Airlines,


Four couples are going to the movie. Each row holds eight seats. Betty and Jim don't want to sit next to Alice and Tom. Alice and Tom don't want to sit next to Gertrude and Bill. On the otherhand, Sally and Bob don't want to sit next to Betty and Jim. How can the couples arrange themselves in a row so that they all sit where they would like?

4 Answers  


How many possible combinations are there in a 3x3x3 rubics cube? In other words, if you wanted to solve the rubics cube by trying different combinations, how many might it take you (worst case senerio)? How many for a 4x4x4 cube?

1 Answers  


A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396. What is the sum of the three digits?

4 Answers  


My friend collects antique stamps. She purchased two, but found that she needed to raise money urgently. So she sold them for Rs. 8000 each. On one she made 20% and on the other she lost 20%. How much did she gain or lose in the entire transaction?

3 Answers   Wipro,






4 men can dig 4 holes in 4 days. How many hours does it take for 1 man to dig half a hole?

8 Answers  


find odd one out among these 25,36,49,64,81

19 Answers   CTS,


foot is related to man in the same way hoof is related to...........

0 Answers  


7 dogs have got 7 puppies each.Each puppy got 7 kittens as friends.They are all members of a club along with me.What is the strength of the club?

29 Answers  


In a hotel, rooms are numbered from 101 to 550. A room is chosen at random. What is the probability that room number starts with 1, 2 or 3 and ends with 4, 5 or 6?

2 Answers  


Six cabins numbered 1-6 consecutively, are arranged in a row and are separated by thin dividers. These cabins must be assigned to six staff members based on following facts. 1. Miss Shalaka's work requires her to speak on the phone frequently throughout the day. 2. Miss Shudha prefers cabin number 5 as 5 is her lucky number. 3. Mr. Shaan and Mr. Sharma often talk to each other during their work and prefers to have adjacent cabins. 4. Mr. Sinha, Mr. Shaan and Mr. Solanki all smoke. Miss Shudha is allergic to smoke and must have non-smokers adjacent to her. 5. Mr. Solanki needs silence during work. Can you tell the cabin numbers of each of them?

1 Answers  


In one year there are 12 months,so how many years in one month

7 Answers  






Categories