# Amazon Interview | Set 26

Hi, I am Mayur Kale,I was recently interviewed for SDE1 position for Amazon in our campus and got selected. Geeksforgeeks helped me lot. I prepared only from Geeksforgeeks.org. I am very thankful to Geeksforgeeks team.

Onw online coding test followed by 4 rounds of F2F interviews.

Online Coding Test (2 Problems,20 MCQs, 1:30 hours) From Interviewstreet
All problems had multiple test cases for which the code was validated against.
1. from input string we have to print character which occurs maximum number of times.

Face to face: Round 1(Technical, 1 hour):
1. Given a boolean matrix mat[M][N] of size M X N, modify it such that if a matrix cell mat[i][j] is 1 (or true) then make all the cells of ith row and jth column as 1 (time complexity expected was O(M*N) and space O(1))
Solution: Boolean Matrix Problem

Code for both questions was required and some other discussion happened..

Face to face: Round 2(Technical, 1 hour):
1. Given string we have insert %20 on each space and input string has enough memory to contain output string.
(time complexity expected was O(n) and space was O(1).

(I told I know this question so he moved ahead..)
3.Given binary search tree in array form and we have to check whether it is fully binary tree or not..
(I gave O(n^2) solution but He was expecting O(n) solution after some discussion I managed to give answer in O(n) complexity…)
4. Given that integers are read from a data stream. We have to find k maximum elements from that stream...
(I gave solution of insertion sort,then come to heap)

code for all questions required and nice discussion was there…
He was very impressed with my answers…

Face to face: Round 3(Technical, 1 hour 20 minutes):

I chose OS…
-some questions on paging and virtual memory.

-If we use 8 GB RAM for 32 bit machine what will happen?
It was nice question..
He was very impressed with answer.
-Some discussion on Networking(DHCP and DNS).
-Some discussion on JAVA.
-Some discussion on DBMS.

-one puzzle
A champagne pyramid is a pyramid made of champagne glasses , each of equal capacity say , n. The pyramid begins with one glass at the top level , two glasses at the second level , then three below that and so on up to infinite levels. A level x of the pyramid thus has x no. of champagne glasses.

A steady stream of champagne is poured down from the top level,which trickles down to the lower levels. What is the distribution of champagne in the glasses at a given level i.
(I told I know this puzzle then he moved ahead..)

-Give a Building with n floor. A person can take 1 step or 2 step to climb. Find the number of ways to reach nth floor. Code was required

Interviewer was very happy after that.

Face to face: Round 4(Technical, 1 hour 20 minutes):
It was like semi HR round.
1. Why Computer science?
2. Given an array of integers which is initially increasing and then decreasing, find the maximum value in the array.
3. Modified k heavy path in binary tree problem.

In evening they told me result and I got selected in amazon. It was very nice experience for me.

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