## Forum Posts

- 0 Answers
**Error in 6th Edition**Maybe you fixed this already in 7th.

- timcrall January 09, 2018

In 6th edition, question 4.11, the question only specifies a binary tree but the answer assumes a binary search tree. Which is exactly a thing you told us to look out for. So I was.

EDIT: Although this doesn't really seem to affect the answer.

Also, for the love of all things holy, invest in some spam-blocking on the forums!| Flag | PURGE - 0 Answers
**String Transformation**You are given 2 Strings A and B. You have to transform A to become B.

- anuj January 07, 2018

Following are the type of transformation possible:

1. pick an alphabet and replace all occurrences of this alphabet in the string by the next alphabet in the sequence[a,b,c,d----y,z]. Note that the next alphabet for z is a. The whole operation counts as one operation with Cost C is given as input.

2.pick an alphabet and replace all occurrences of this alphabet in the string by the previous alphabet in the sequence[a,b,c,d----y,z]. Note that the next alphabet for a is z. The whole operation counts as one operation with Cost D is given as input.

You have to return the minimum cost to transform A to B. if it's not possible return -1

Example:

A: "ab"

B: "cc"

C:2

D:5

Answer : 4

we need two C operations "ab" -->"bb"-->"cc"

Note that the last step of converting all b to c counts as one operation| Flag | PURGE - 0 Answers
**Didn't receive any offer**Hi,

- stan.alexandru.dan November 30, 2017

I've held the interview process at Amazon for a position in one of the european offices.

So I got contacted by a recruiter, I did an online test, afterwards a phone interview, after that on-premise interviews.

I had 4 on-premise interviews, each a one-on-one with a Software Manager, 2 of them were algorithms, 1 was architecture and another was Software Design.

After 2 weeks I received a call from the recruiter. She told me I've passed the interview process, but there was predicament and I will not be receiving an offer from the center I applied to, and I will receive an offer from another european office on the same day.

3 months have passed, I haven't received any offer and the recruiter stopped responding, I have sent several mails and still no reply.

I still don't know what happened, my resumee wasn't that good, was my application lost in the process.

I don't know if it's worth trying again, if things like this happen. I know I've spent a full month, preparing, not sleeping well. I've never felt prepared for the interviews, also I wasn't outstanding on them, going through that again seems a bit much.

What do you guys think, should I try again, has anyone else had the same experience?| Flag | PURGE - 0 Answers
**Developing Java game**creating a RESTful service using which players can play a simple game described

- stallapp November 02, 2017

below.

The game should have the following rules:

• The player has an infinite amount of coins.

• The player bets 10 coins to play a normal game round.

• In any round (free or normal), the player has a 30% chance of winning back 20 coins.

• In any round (free or normal), the player also has a 10% chance of triggering a free round where

the player does not have to pay for bet. The free round works in the same way as a normal round except

it costs 0 coins. The free round should follow immediately after the normal round.

• The player can both win coins and free round at the same time.| Flag | PURGE - 0 Answers
**rejected by amazon for no reason**got rejected, I think I did well for all rounds, maybe not behavioral questions. They didn't give any feedback.

- ly October 21, 2017

the questions were not hard at all.

one round, I only got asked behavioral questions for 45 mins. really not that much to say

disappointed| Flag | PURGE - 0 Answers
**Data Structure and Search Design**Question:

- Learneralways August 18, 2017

You are given an information on Cat object such as name,height and weight. For eg following:

String[] names = {"a","b","c","d","e","f","g","h"};

Integer[] height = {31,24,67,12,45,21,31,12};

Integer[] weight = {120,124,160,130,175,120,124,142};

You have to write a method which takes the following input and return the list of Cat objects which satisfies the input criteria. For eg

searchCriteria could be : HEIGHT or WEIGHT

searchValue could be : Integer value of either HEIGHT or WEIGHT

symbol could be : "<" , ">", or "="| Flag | PURGE - 0 Answers
**Is Amazon Joking Around?**Amazon is known for its tough tech screening rounds but even if you nail those technical question with best possible solution, are you getting screwed??

- hprem991 August 04, 2017

Before this experience, I would have said NO but now it is looking different..

I was being picked up by their recruiter and asked to present myself for phone screening as they liked my experience (thats what they said ).

Now, I wouldnt mind.. being the fact that I am doing great in what I am doing.. its just a 1 hour call.

Well, call lasted for like 55 mins.. Was asked 2 algorithmic questions with code and follow ups and some pretty team / experience related question..

I nailed the tech rounds so much that the interviewer said, I got questions done with most optimal solutions and of course before time.

So, if they liked my experiences ( thats what they said they called me at first place).. Did they rejected me for same experience or Amazon interview has become a joking ground now?

Any thoughts??| Flag | PURGE - 1 Answer
**Design a FIDS(Flight Information Display System)**1. Consider most important classes & ignore Interfaces as of now

- AD August 04, 2017

2. FIDS is not about reservation system but the dasboard to display

3. the information will look like:

DEPARTURES

----------------------

Attributes:

STD, Airline,Flight#,Destination/Via,CheckInCounter#,Gate,Status,ETD

Values :

12:50,KingFisher,6E352,Hyderabad,A-B,23,Check-In Open,13:15

ARRIVALS

-----------------------

Attributes:

STA,Airline,Flight#,Destination/Via,Gate,Status,ETA

Values :

12:50,KingFisher,6E352,UK/Mumbai,Terminal2,Landed,13:15| Flag | PURGE - 0 Answers
**Minheap: TLE**The following is my code for MinHeap. But it is showing TLE for some input. Can someone please help me figure out where?

- ranjani4ever July 14, 2017

#include <cmath>

#include <cstdio>

#include <vector>

#include <iostream>

#include <algorithm>

using namespace std;

void swap(int *a,int *b){

int temp=*a;

*a=*b;

*b=temp;

return;

}

void heapify(vector<int> &heap,int index)

{

int length=heap.size();

int min=index;

int left=(index<<1)+1;

int right=(index<<1)+2;

if(left<length&&heap[left]<heap[min])

min=left;

if(right<length&&heap[right]<heap[min])

min=right;

if(min!=index)

{

swap(&heap[index],&heap[min]);

heapify(heap,min);

}

}

int main() {

int t,n;

string op;

scanf("%d",&t);

vector<int> heap;

while(t--) {

cin>>op;

//cout<<"Currently analysing"<<op<<"\n";

if(op=="insert") {

scanf("%d",&n);

heap.push_back(n);

int i=heap.size()-1;

while (i!=0&&heap[(i-1)>>1]>heap[i])

{

swap(&heap[i], &heap[(i-1)>>1]);

i =(i-1)/2;

}

}

else if(op=="getMin") {

if(heap.size()>0)

printf("%d\n",heap[0]);

else

printf("Empty\n");

/*for(int i=0;i<heap.size();i++)

cout<<heap[i]<<" ";

cout<<"\n";*/

}

else {

if(heap.size()>0)

{

heap.erase(heap.begin());

heapify(heap,0);

}

}

}

return 0;

}| Flag | PURGE - 0 Answers
**Amazon question**At Amazon.com, users log in and access random pages numbered as 1,2,3… Given at any time, you need to tell the most popular sequence of 3 pages visited by users.

- yeswanth June 28, 2017

Eg.

At some time t,

U1: P1, P2, P3, P8, P1, P2

U2: P8, P1, P2

O/P: P8, P1, P2

At time t+1, say

U1: P1, P2, P3, P8, P1, P2, P3

U2: P8, P3, P2

O/P: P1, P2, P3| Flag | PURGE - 0 Answers
**Question**There are around 40 million files in a directory which needs to be transferred to another system via FTP in order of oldest file first. What's the ideal way to iterate over files and store it in a data structure from where it can be transferred?

- anjesh June 12, 2017| Flag | PURGE - 0 Answers
**qwrew**A mission-critical production system has n stages that have to be performed sequentially; stage

- tanvirmahmud201505039 June 08, 2017

i is performed by machine Mi. Each machine Mi has a probability ri of functioning reliably and

a probability 1 − ri of failing (and the failures are independent). Therefore, if we implement

each stage with a single machine, the probability that the whole system works is r1 · r2 · · · rn.

To improve this probability we add redundancy, by having mi copies of the machine Mi that

performs stage i. The probability that all mi copies fail simultaneously is only (1 − ri)mi, so the

probability that stage i is completed correctly is 1 − (1 − ri)mi and the probability that the whole

system works is Qni=1(1 − (1 − ri)mi). Each machine Mi has a cost ci, and there is a total budget

B to buy machines. (Assume that B and ci are positive integers.)

Given the probabilities r1, . . . , rn, the costs c1, . . . , cn, and the budget B, find the redundancies

m1, . . . , mn that are within the available budget and that maximize the probability that the

system works correctly| Flag | PURGE - 0 Answers
**Designing a data-structure**We need to implement a data-structure for following functions

- arnav251035 May 29, 2017

Insert X : Insert an element X into the set.

Delete X : Delete an element X from the set. It is guaranteed that such X always exist in the data structure.

Mean : Report Mean of the elements present in the data set. It is guaranteed that data structure will not be empty at this query.

Mode : Report Mode of the elements present in the data set. It is guaranteed that data structure will not be empty at this query.

Median : Report Median of the elements present in the data set. It is guaranteed that data structure will not be empty at this query

I had created a linked list of the values, and like insertion sort I inserted the elements in the Linked List. Deletion was also the same as deletion in Linked List. Mean I calculated on the run as and when the values came. For mode I traversed the whole linked list to see which element occurs the most. Median was the middle element in the linked list.

I know there is an efficient algorithm to calculate median on the run using two heaps (min and max) but calculating mode was the biggest problem I faced. The number of queries ranged to 10^5 and the time limit was given 3 secs. Had a TLE error| Flag | PURGE - 0 Answers
**6 to 8 months project ideas to build up résumé**Hello,

- otto.alyz April 18, 2017

I'm planning to go through big IT companies interviews (basically the GAFAs) in 8 months from now, and I would like to get some suggestions about ideas of projects I can work on to present during my interviews and build up my résumé.

I ideally looking for a project that would make me practice the OOP principles like SOLID, as well as other things like scalability, algorithms and data structures and so on.

Thanks in advance for your suggestions.| Flag | PURGE

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