# Amazon Interview | Set 31

Recently I attended the Amazon walk-in and got selected for the position of SDE I.

Written test:

1. Write a code to convert tree to DDL(assume tree node contains pre, next pointers and set as null intially.)

2. WAP to encode and decode string.
aabbbbcccd <->a2b4c3d1

3. Find the sum of elements in after nth iteration for below operation on array.

```   original array  4 6 8 3 6    sum = 27
iteration1      -2 -2 5 -3    sum = -2   (a1= a2-a1)

iteration2:     0  -7  8     sum= 1

iteration3:       7  -15     sum =-8 ```

Hiring Manager:

1. Find the nearest leaf node from given node in binary tree..
use post order traversal.. like LCA in binary tree
2. Find the first k largest numbers from large file size. Explain solution for

1. When we have space to store K elements in RAM

2. When we didn’t have space to store K elements in RAM

Tech:

1. Design N-ary tree, to make sure that lock and unlock operations can be done with minimum complexity (height of tree)
a node can be locked when its ancestors or successor are not locked.
we can a unlock a node a any time.
2. a[] = {a,b,c,d,e} b[]={f,g,h} result should be = af+bg+ch+df+eg

Tech:

1. Find maximum product of subarray in given array of integers
2. Design T9 dictionary

Bar Riser:

1. Design a tree, in which a root can have unlimited children and write a code to print each level in separate level

2. Print the anagrams present in a huge file (each line in file contains one word and you didn’t have any constraints like limited memory etc..) for a give string

use trie or hashmap

Like all Amazon interviews in GFG, here interviewer more concerned about edge cases and perf perf perf perfect code.

Thanks a lot GEEKS FOR GEEKS and my dear friends Ramesh, Purush, Jhadey for helping me in preparation.

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