CareerCup

You have a database table that stores information about the price change of various product with time. It's append only table. Whenever the price of the product p1 is changed to c1 at time t1, a new row will be appended.
product_id price time
p1 10 4
p2 40 4
p1 20 5
p1 25 6
p2 55 7
...

Write an SQL query that will give the price of every product at time t1.
e.g. at time 6
product_id price
p1 25
p2 40

Note: Consider the case where two updates are made at the same time. Don't assume that the table is sorted by time.

Write a program to sort a string without using java API?
I/P : "a390testai"
O/P: 039aaiest

Design a hit counter which counts the number of hits received in the past 5 minutes.

Given an array A[] consisting 0s, 1s and 2s, write a function that sorts A[]. The functions should put all 0s first, then all 1s and all 2s in last.

You are given a list of n-1 integers and these integers are in the range of 1 to n. There are no duplicates in list. One of the integers is missing in the list. Write an efficient code to find the missing integer.

Write an efficient program to find the sum of contiguous subarray within a one-dimensional array of numbers which has the largest sum.

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

Design payments system like Google Pay or Paytm.

Design QR code system for a grocery shop.

You have a bit pattern and an infinite stream of bits coming in. You need to raise an alarm whenever the given pattern comes. Storing the stream is not allowed.

Design a Notification Service. Notification can be sent to multiple devices.

Design a job workflow system wherein a job is defined as sequence of steps. This system will take jobs and execute as per the steps in job. The steps can be conditional(if this then do this else do that). This system should be able to handle multiple jobs, should be fault tolerant etc

Design and implement a Message broker which can handle high throughput and is fault tolerant.

Design a workflow system. You need to implement pause/continue operations of the workflow using your database. Essentially, the interviewer was looking completely manage workflow system using database.

Design a finite state machine

Design slack like collaboration tool

There is a notepad which accepts only four operations:
1. Character X
2. select all
3. copy
4. paste
Given n number of operations, provide the sequence of choices that gives maximum characters in the notepad.

Given two async streams -
Trip : {tripId, date, city}
Bill: {billId, tripId, date, amount}

Design a system to get real time aggregated view of following nature
City, TripCount, TotalAmount

Events in both streams can be out of sync or duplicate. But result needs to be accurate and realtime.

Design a Scheduler Service which can handle high throughput with minimal latency. Should be fault-tolerant and distributed.

Design a log4j style logging library for a high throughput multi threaded application.

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