# Amazon Interview | Set 7

Hi my name is Anandhakumar. P. I am a 2012 pass out from college of engineering guindy. I recently underwent offcampus interview with Amazon, Chennai, India for the post of SDE. I love geeksforgeeks and i will call it as the best site to prepare for coding interviews. Here goes my interview experience. Hope this is useful to someone and someone gets benefitted by it.

**Written test** [1 hr 15 min duration]

Three questions were asked.

**1)** Check whether a tree is balanced.

**2)** Reverse k nodes in a linked list.

eg 1->2->3->4->5->6->7->8->9->10->11 [k=3]

answer must be [3->2->1->6->5->4->9->8->7->11->10]

**3)** arr1 – 4, 5, 6, _, _, _

arr2 – 1, 2, 3

arr1 has enough free space to hold elements of arr2. Merge array 2 with arr1 in a sorted manner.

Cleared this round. I felt it easy as i was preparing for it for more than 2 months and geeksforgeeks helped me greatly.

**1st face-to-face interview** [1 hr 15 min ]

Short description about myself

[2 min alone. Just told my name and my most important project for which i won ipad 2]

**1)** An array of size n is given. The array contains digits from 0 to 9. I had to generate the maximum number using the digits in the array such that it is divisible by 2, 3 and 5

eg: 1 array = 18760, output must be: 8160

eg: 2 array = 7776, output must be: “no number can be formed”

[discussion went for more than 35 minutes. Every time i gave a solution, he was adding the constraints and finally i did it. he was ok with it.]

**2)** least common ancestor in a binary tree [Note : not binary search tree ] [30+ minutes]

I explained him with several methods and finally he was ok with and asked me to write the code for and i did it. he checked my code for different test cases and finally he was ok with it ..

Not even 5 minutes break i was asked to get ready for next face to face interview .

**2nd face to face interview **[1 hr 20 min ]

Short description about myself [2 min alone. just told mmy name and my most important project for which i won ipad 2. dont tell too much. they just wanted to know a little about u . inshort ur name and college. ]

**1)** zig zag traversal of a binary tree. [35+ min ].

Man i have studied this in geeksforgeeks and wrote him the code using recursion, which was working perfectly. But he told me to use reduce the complexity by using any data structures. I told him a logic using a stack and a queue. Another logic using 2 stacks . But he wanted me to use only one data structures. I tried using a single queue and he to helped me a little and finally he was ok with it .

**2)** A n*n matrix is given which is containing elements in which each row alone is sorted. column is not sorted. I have to convert it into a single dimensional array which will hold all the elements of the array in a sorted manner.

I told him many logics . actually he kept on adding constraints with whatever logic i told him. Finally he gave me a hint and asked to use minheap property and finally he was ok with it. I solved this question using lots of help with him. man i was in interview for continuously more than 3 hours.

I am waiting for my result for next round. I will update if i go through the next rounds. Overall it was a great experience with amazon and people in amazon are very smart minded.

Hope this is helpful to someone!

Thanks to **Anandha Kumar** for sharing Amazon Interview experience. If you like GeeksforGeeks and would like to contribute, you can also write an article and mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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