# Amazon Interview | Set 37

Interview Experience for placements at AMAZON.
It consists of 1 online round (20 MCQ + 2 coding question) and 4 F2F interviews.

Online Round 1:
20 MCQ 1 question each from OS, pigeon hole principle, probability, DBMS, networks, NP problem and other questions from C/C++ input output and logical question

22 from batch out of 300 students were selected for F2F interviews

Interview Round 1:
As they were short in time as it was 9 at night so they asked me single coding question.
Que 1: Given an array of n numbers with repetition of numbers. You need to find the max length of continuous sub array with at max 3 unique elements.
For eg
array: 1 2 3 1 4 3 4 1 2
ans: 6 (3 1 4 3 4 1)
Solution: Time complexity O(n)
Extra Space O(1)

Interview Round 2:
They asked me 3 questions but I am not remembering the 2nd one. Sorry for that
Que 1: You are given two binary trees. You need to tell that if one tree is rotated 90 degree and placed at bottom of that tree and each leaf nodes at max depth of two trees will meet each other or not.
for eg:
lets assume () as a node
Tree 1

```
(1)
/  \
(2)  (3)
\   /
(4,5)
node 4 and 5 are overlapping
Tree 2
(1)                     (4)
/   \                      \
(2)  (3)  => Rotated one    (2)  (3)
/                             \  /
(4)                            (1) ```

So it returns true as node 4, 5 of tree 1 is overlapping with node 4 of tree 2
Firstly I was asked to give algorithm then when i gave he asked me to code it
Solution: Time Complexity O(n+m) (where n and m are nodes in tree 1 and tree 2 respectively). Space Complexity O(n+m)

Que 3:
Suppose u given normal deck of cards 4 suites and 13 cards of each suite in which one card is missing
you are picking a card one at a time and sees that card and putting it aside
Find the suite and number of missing card.
Then he said change the number of suites to K (very very large you cant add till k)
and N numbers (again very large numbers)

Interview Round 3:
It was an easy round for me atleast but not for others
Que 1: Find the palindrome of a given number without using extra space

Que 2: 100 floors and 2 egg problem changed to 50 floors and 2 eggs

Que 3: You are given array of numbers which increasing first then decreasing. Find the greates number.
eg: 1 2 3 4 5 4 3
Solution : Time Complexity O(logn)
Space Complexity O(1)

Interview Round 4:
He asked me about my myself apart from coding and as I said “Hacking” so we discussed about hacking a lot.
He also aksed me about my projects
Then he gave me a puzzle:
Assuming I have a chessboard (8X8)
a knight is placed at (x,y) and he moves N hops
Find the probabilty that he will be inside after N hops.
On a condition that if a knight moves outside then he will remain outside he cant come inside.
For eg. (x,y)=(0,0)
n=2
probabilty=(12/64)

4th round was type of HR as he wants to know about myself and how I do different things.
If I stuck in a position what will I do.
If your boss says that you have to do X and you are not satisfied with this then what will you do and how will you approach.

After that I waited for 3 hours and I got selected with 4 of my friends 😀

Hope this will help, I try the possible way to support you.

All the best for your placements 🙂

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