Sort A, B, C, D and E

Logic Level 2

There are 5 people, A , B , C , D , E A, B, C, D, E that are standing in a line facing to the left. A A can see no one, while E E can see everyone. Starting with A A , each of them is asked "How many people standing before you are also taller than you are?". The replies from each of them were 0, 1, 1, 0 and 1 respectively.

Arrange these 5 people according to their height, starting with the shortest.

Note: Assume that no two people have the same height.

BAEDC BACED ABCED BCAED

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Farhabi Mojib by Farhabi Mojib , 23, Bangladesh

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5 solutions

Nisarg Thakkar
Apr 11, 2014

A-B-C-D-E are standing in this order.

  • A will obviously reply 0,
  • B says 1 so, A>B
  • C says 1, so B cant be taller than C, otherwise C's reply would be 2. so, from this, we get A>C>B
  • now, D says 0 so he is the tallest among A,B,C, and D
  • E says 1 so applying same logic as in C's case above, we get D>E>A>C>B.

we want in ascending order, so BCAED.

109 Helpful 0 Interesting 0 Brilliant 0 Confused

Ugh! I really need to observe more carefully.

A Former Brilliant Member - 7 years, 1 month ago

If E is shorter than D, how can E see everyone ?

Chandrodoy Chattopadhyay - 5 years, 4 months ago

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Had the same question. Probably everyone can see all others in front them except A obviously. We can also infer this by the answers, none of which has E as the taller.

John Miller - 5 years ago

'E' is not a machine that he cannot jump or tilt sideways... :)

Avinash Kamath - 4 years, 6 months ago

How is this related to computer science?

Adarsh Kumar - 7 years, 1 month ago

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In an array ordering, obviously.

Normando Mendonça - 7 years, 1 month ago

why doesn't this question bring into account of the fact that having a taller guy in front of you will block your vision ?

InkWhite 2000 - 5 years, 1 month ago

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'E' is not a machine that he cannot jump or tilt sideways... :)

Avinash Kamath - 4 years, 6 months ago

wow!good solution

Ayush Sharma - 5 years, 10 months ago

poorly worded question; I assumed no-one can see past a taller person in which case there is no solution. Looking at the answer I realise that my assumption is wrong else E would only 'see' D (the others being obscured). . Also if you are facing left there is no-one 'before' you. Bad English

Stuart McGuinness - 4 years, 8 months ago
Frodo Baggins
Apr 15, 2014

Since B says 1, A is taller than B. C also says 1, so either A or B is taller than C, but if B was taller than C, then A would be too and C would have said 2. The only option with A taller than B and C is BCAED.

11 Helpful 0 Interesting 0 Brilliant 0 Confused
Levi Titan
Jul 20, 2014

ABCDE 01101. This is just sorting from left to right. Person A sees nobody taller so he stays in position. Person B sees 1 taller so switches places with A. The numbers are now 00101

Person C sees 1 person taller so switches places with B. 00001

ABCDE = 01101

BACDE = 00101

BCADE = 00001

BCAED = 00000

You can infer from this that you just move from left to right. If the letter is 1 it switches places with the letter left of it. If the letter = 0 it remains in position.

8 Helpful 0 Interesting 2 Brilliant 0 Confused
Lokesh Chauhan
May 25, 2014

ABCDE are arranged facing left When A says 0, there's no one taller than him When B says one, it means A is taller than B So the sequence now will be BACDE Now again C said there's one bigger than him. So the sequence now will be BCADE And there's only one option with BCA in starting So no need to check others.

3 Helpful 0 Interesting 0 Brilliant 0 Confused

0 Helpful 0 Interesting 0 Brilliant 0 Confused

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