# Amazon Interview | Set 52 (For Internship)

• Difficulty Level : Medium
• Last Updated : 18 Jun, 2019

Hi All, Here is my interview experience with Amazon for internship. Hope it helps:

Round 1:

Online round with 20 objective questions on (Questions related to data structures, analysis of algorithms, C Language and some puzzles.) and 2 coding questions in 90 minutes

1. Write a program to reverse k alternate nodes of a linked list
```Ex: 1->2->3->4->5->6->7->8->9
If k is 3 Output should be: 3->2->1->6->5->4->9->8->7```
2. Given a string. Write a program to form a string with first character of all words.
```Ex: The bucket is full of water
Output: Tbifow```

Check all edge and corner cases.

Round 2: Face to face round

1. Given a binary tree. Modify it in such a way that after modification you can have a preorder traversal of it using only right pointers. During modification you can use right as well as left pointers. Write complete code and dry run it for some test cases.
2. Given 2 linked lists. Find out if they intersect or not. If yes, find intersection point .Write complete code for it.

I could not remember the simple way: find the length of the lists and simply move forward the shorter list by difference of the lengths and find the intersection point. Instead, I joined the end of first list at the end of the 2nd list and then went for cycle finding by Floyd Cycle finding Algorithm. Although both are O (n), but he was impressed as it was a new approach.

Round 3: Face to face round

1. Given a sorted array of 0’s and 1’s. Find out the no. of 0’s in it. Write recursive, iterative versions of the code and check for all test cases.
2. Spiral level order traversal without using extra variable for detecting level (using one stack and one queue) and few other implementations as well.

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