CareerCup

Design a vending machine with following functionalities
Three types of Users : User, Operator, Admin
User can select and buy multiple items at a time. Money can be inputted multiple times (you will get the item if there is a time gap > 30 secs). He can also do window shopping (see only the prices of items and buy nothing)
Operator can load the items and mark the items as expired if needed, gets notified if a product goes out of stock.
Admin can own multiple vending machines, he should have a analytics report of the items purchased in a month. He can also change the prices directly and it should reflect in all the vending machines which he owns.
Exception handling in all the edge cases
Both HLD and LLD were expected.

You have been given a set of inter-dependent tasks along with the time taken to execute them. We have more number of parallel processors available than the number of tasks given. There could be multiple starting tasks. There could also be cyclic dependencies. Calculate the minimum time required to complete all the task.

Find a subarray with a give sum

Count number of strings of length N with following properties:

A. Consists of char 'A' and 'B' only.
B. There is atleast one occurrence of 3 consecutive Bs.

Input: Only line having integer N.

Output: Number of string with given properties. As then number can be very large print it with modulo 10^9+7.

Sample Input 1:
3

Sample Input 2:
1

Explanation: Only possible string "BBB"

Its farewell day, there are total N students, every student has bought a gift to give. He/She will give this gift to some other student. After gifting process is over, you are given an array, representing number of gift student receive i.e. ith number denoting number of gift he/she got. Your task is to find, whether given gift count array is valid or not. If it is valid print any of possible way of gifting that lead given array.

PS: Student can't gift to himself. Student has exactly one gift with himself.

Input: First line will have one integer M, denoting number of students. Next line wil have N spaced integers denoting number of gift student gets.

Ouput: -1, if given gift received array is not valid else print N spaced integers denoting ith gifted to jth.

Sample Input 1:
3
1 1 1

Sample Output 1:
2 3 1

Parking lot problem: Given 3-dimensional parking lot, lets say, length width and floor. Implement following two methods:
void unpark(int i, int j, int k); where i, j, k are the parking coordinates.
void park(); The car should be parked in empty cell with lowest floor and between length and breadth prefer minimum length.Example, (3, 4, 2) is preferred over (1, 1, 3) as floor is 2 in first case. (1, 2, 3) is preferred over (2, 1, 3). (2, 3, 3) is preferred over (2, 4, 3).

Given an array find if array gets sorted by reversing any subarray of this array. Ex: In {1, 2, 3, 4, 8, 7, 6, 9} we can reverse subarray from index 4 to 6.

LLD for third party delivery vendor for registration and notification system.

Design gaming platform. A number of games can be hosted on this platform. User can login and select a particular game.

Design Meeting calendar system. Then there was discussion on various issues on it like scalability, what database should be used; SQL-NoSQL, concurrency etc.

You are given many files of 6 GB, each having stream of integers. You have space of 4 GB left in your main memory (mainly to swap out, swap in). You have to store sorted sequence of integers in all file in a other output file. How will you do that?

Design an authentication using AWS services like Api gateway and lambda.

Design an online chess game.

It supports 3 mode:
Player vs. AI
Player vs. player  (Offline)
Player vs, player (Online)

The questions asked were how will you assign a player to another player who wants to play. You need to think about how to divide your players into multiple groups of ratings, so that a newbie is not playing a grand master, rather with someone who is of his level only. Then the question was how will you design your system when a player comes in and say I want to play, and the max wait time is 1 min, you need to find a player suitable for his level

Design a movies reviews aggregator system. Data should be fetched from movie rating providers like imdb, rotten tomatoes, etc

Find the sum of n elements after a kth smallest element in BST. Tree is very large, you are not allowed to traverse the tree.

Design subscription based sports website which can display scores, game status, history for any games hld and lld

Consider an infinite stream of numbers. At any point print smallest k elements.

Given an array of integers(duplicates allowed) return if it is a set of contiguous integers or not?
Input: 5,2,3,6,4,4,6,6 Output: Yes (as it is from set of [2,3,4,5,6])

Given an array of integers with the property that arr[j] – arr[j-1] is either 1,0,-1 and a search value, provide an efficient search mechanism.

Given coin denomination of 3, 6 and 17, find the number of ways in which you can form a sum 'n'. How will do it for large numbers?

There is a huge road. Given are the following
- Array D that stores the distance from a starting point where billboard can be installed.
- Array C that stores the profit. C[i] -> profit if the billboard is installed at distance D[i].
- dist -> minimum distance to maintain between the billboards.

Assume you can install any number of billboards while maintaining a given minimum distance 'dist' between each of them. Find the maximum profit you can achieve.

Design an airport service that will be used to allocate a free runway when the plane is about to land. Data structure for the same. What if the runway is not available? Message passing between control centre and the plane. Focus on low-level design and code. Can the same runway be alloted to two different planes (locking)? Database storage needed?

How to find if a Binary tree has an odd number of nodes without using node count? Binary tree does not have to be balanced

C program for the given two array as point of x and y
int x[] = { 2,3,2,4,2};
int y[] = {2, 2, 6,5,8}; count the pair
maximum area coverd in x y plane
Ouput:3
From the above input there are five coordinates possible (2,2)(3,2)(2,6()(4,5)and (2,8) in which (2,2)(2,6)(2,8)that is three coodinaters covers the maximum area in x y plane
Input: x[] ={1,2,3}
Y[] = {1,2,3}
Output: 1
there are three coordinates (1,1)(2,2)(3,3)in which only one coordinates covers maximum distancethat is (1,3)

Program to print last element of matrix by traversing a matrix by anticlockwise starting from cell(1,1) and skiping alternate.
Ex:
Input:1 2 3 4
2 4 5 1
7 9 6 2
3 5 2 7
Output: 5
Start traversing matrix from cell(1,1) skip next row element go to 3 row element again skip 4 element go to bottom of second column .....up to last element and print only last element.
If Input: 1 2
3 4
Output: 2
Input:1 2 3
4 5 6
7 8 9
Output: 5

Print all possible combination by replacing special charecters from number.

Find the indices of all anagrams of a given word in a another word.
For example: Find the indices of all the anagrams of AB in ABCDBACDAB (Answer: 0, 4, 8)

Write AWS lambda function to fetch data from on premises oracle db and migrate to aurora db.

I tried :

var oracledb = require('oracledb-for-lambda');
var os = require('os');
var fs = require('fs');
'use strict';

str_host = os.hostname() + ' localhost\n';

fs.appendFile(process.env.HOSTALIASES,str_host , function(err){
    if(err) throw err;  
});

Can someone show me , i have table with same columns present in oracle db as well as aurora db i want to map form oracle to aurora. How to write it in java or python using aws lambda.

Design a data scrubber.

Say a customer couldn't use Alexa with Philips light bulb. Now customer calls to Alexa/Amazon customer support they figure out the issue is not with Alexa it's with the Philips LED bulb.

Now amazon will redirect their customer call / chat to third party customer support (Philips in this case).

Now somehow we need prevent the possibility of third party customer support trying to exploit our customers. For ex: asking their bank accounts, credit card, Social Security number etc..

How will you do that for AMAZON level ?

You have oracle database table , and AURORA AWS table with same fields , write a java lambda function to migrate data from oracle table to aurora. Also it should be realtime, if a new record is added to oracle it should update aurora db table as well.