CareerCup

You're given an array of integers sorted ( [1,2,3,5,6,7,10]) you need to serialize and compress this array into a string (1-3, 5-7,10)

Given two points on a directed acyclic graph determine their least common ancestor, give it's time complexity, and describe any improvements you could make (if possible).

Use synchronized, wait() and notify() to write a program such that below mentioned conditions are fulfilled while reading and writing data to a shared resource.

When a write is happening, no read or other write should be allowed(read and write threads should wait)

When a read is happening, no write should be allowed (write threads should wait) but. other read threads should be able to read.

Donot use any API classes e.g. ReadWriteLock, AtomicInteger etc..

Design election voting system. Election would be country wide. System should be scalable, available and consistent.

Implement following method of ScheduledExecutorService interface in Java

schedule(Runnable command, long delay, TimeUnit unit)
Creates and executes a one-shot action that becomes enabled after the given delay.

scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit)
Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given period; that is executions will commence after initialDelay then initialDelay+period, then initialDelay + 2 * period, and so on.

scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit)
Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given delay between the termination of one execution and the commencement of the next.

Given a string select two non-overlapping strings that are same and remove them. Perform this operation recursively till there are no desired strings.
Print the number of possible substring after completing above operation.
Ex - abcc
Duplicate non-overlapping substring - abc
After removing abc from we are left with 1 substring abc.

In a 2-D matrix of m*n select m-1 elements from each row such that that the resulting sum is minimum and each column is selected atleast once.

Ex -
2 3 5
3 2 5
4 4 7
Selecting (2,3) from 1st row, (2,5) from 2nd row and (4,4) from 3rd row would result in minimum sum of 20

Find LCA for list of nodes of a tree

Function defined as below -
TreeNode findLCA(TreeNode root, List<TreeNode> nodes)

Given two numbers m and n. Find all numbers between these two numbers such that difference between adjacent digit is 1
For ex m =0 n =22
O/p - 0,1,2,3,4,5,6,7,8,9,10,12,21

Code an algorithm for a game consisting of two players. The input is a positive integer x. Each round, a player deducts a perfect square from the number. The player can choose any perfect square as long as it is less than or equal to the current number and greater than 0. The current player wins if the number becomes 0 after his deduction.

P0, P1, ...., Pn players in tournament. In first level, P0 plays with P1, P2 plays with P3 and so on. In level 2, Winner of P0,P1 plays with winner of P2,P3. For i,j output level in which they will face each other assuming they win all games.

Given a nested list of integers, return the sum of all integers in the list weighted by their depth.

Each element is either an integer, or a list -- whose elements may also be integers or other lists.

Different from the question where weight is increasing from root to leaf, now the weight is defined from bottom up. i.e., the leaf level integers have weight 1, and the root level integers have the largest weight.

Example 1:

Input: [[1,1],2,[1,1]]
Output: 8
Explanation: Four 1's at depth 1, one 2 at depth 2.
Example 2:

Input: [1,[4,[6]]]
Output: 17
Explanation: One 1 at depth 3, one 4 at depth 2, and one 6 at depth 1; 13 + 42 + 6*1 = 17.

Use the location data getting generated from multiple delivery boys moving on the ground to estimate time which a delivery boy will take to move from point A to point B in an area. Additionally, try to do this in real time so that it can be used in assigning delivery boys and minimising delivery time in real time.

In a binary tree if the neighbours are set on fire for every node , find the path to optimally set the entire tree on fire.

Given an input stream of Swiggy order timestamps and costs, at any instant find the costliest order in the last X mins

Design a system to upload images with tags. The tags should be searchable and search should return images linked to those tags.

I dont remember the exact problem anymore. but the problem's solution included going through an array and at every step taking 2 minimum element and adding the result. this also includes the result itself.

so lets say for following array:

2,54,4,10,1,7

you first take 1 and 2 and add
then add the result 3 to the array
so now your array looks like :
3,54,4,10,7

then you take 3 and 4 and add them and add result back

I basically used a heap where i take two mins and add them and add the result back to heap.

I have give amazon online test twice in last 8 months and both the times the first question was about heaps and second something about finding shorted path in a grid between two cells

The problem was very similar to the problem from geeksforgeeks:

Shortest distance between two cells in a matrix or grid
Given a matrix of N*M order. Find the shortest distance from a source cell to a destination cell, traversing through limited cells only. Also you can move only up, down, left and right. If found output the distance else -1.

instead of source and destination, they asked for robot to be able to get rid of obstacle at a certain cell.


I have give amazon online test twice in last 8 months and both the times the first question was about heaps and second something about finding shorted path in a grid between two cells

Design amazon online book store.

I am given jobs with starttime and end time and we unlimited VMs. at any point a VM can only take one job. so bascially I had to find overlapping jobs and assign them to different machines and those that are not overlapping could be assigned to same machines. The tricky part was when there are two different overlaps and they could be assigned to 2 machines instead of all overlapping jobs being assigned to different machines.The method should return minimum number of VMs used to finish all jobs.

I mentioned sorting the jobs based on start time. and then returning number_of_overlapping jobs +1. but again in some cases if there are two different overlaps which could be assigned to two machines then we need to take care of that.

Expression tree evaluation and also write the class for the node and tree itself. (just basic structure like node and data)

LRU cache. Basically started off with how would I store values and get them from memory for faster access. So I mentioned HashMap. and then interviewer added more info about deleting least recently used element.

Given movement of Robot -
G-GO one unit
L-Turn left
R-Turn right

Given an input of string have to find whether there exists a circle which the robot would traverse. Input of string is the set of G,L,R have to return yes or no.

Given a list of strings. Check whether any two strings, if concatenated will form palindrome or not.

There is a hierarchical structure in an organization. A party is to be organized. No two immediate subordinates can come to the party. A profit is associated with every person. You have to maximize the total profit of all the persons who come to the party.

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.

How will you implement organizational chart? Implement two methods -
isPeer - Should return true if two employees have same managers.
isManager - should return true if manager is management chain of given employee.

Relation between 2 animals is given.
A is child of B
C is child of B
A is child of D

An animal can be child of 0 to 2 parents. With this given data, find out if two animals are related to each other.
Follow up question was - Maternal side animals, should not be related to patrernal side family.

You have a 3x3 grid. In each cell you can have two colors, white or black. At the beginning, the matrix has some cells painted white and others black.
If you change a color cell, that is, grid [i] [j] the cells grid [i-1] [j], grid [i + 1] [j], grid [i] [j-1] and grid [ i] [j + 1] also change (if these positions do not leave the 3x3 grid), that is, if they were white, they change to black.
Return, the minimum number of cells you have to flip for the 3x3 grid to be totally white. If you cannot do this, return -1!
Sample input/output - ibb.co/3Y0WVNR