## 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
**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
**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

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