CareerCup

Given a array of integers find the index which partitions the array to two with high numbers and low numbers. For example [5, -1, 3, 8,6] the index 3 will partition the array to [5,-1,3] and [8,6] all the numbers in the second partition are greater than first. The solution has to work in O(n).

Given an n-ary tree and some queries for the tree, in every query you’ll be given a node you are supposed to print preorder traversal of the subtree rooted at that node.

You have an array of numbers. You have to give the range in which each number is the maximum element. For Example, If array is 1, 5, 4, 3, 6 The output would be
1 [1, 1]
5 [1, 4]
4 [3, 4]
3 [4, 4]
6 [1, 5]

Given an array of billion of numbers. Billions of queries are generated with parameters as starting and an ending index. Both these indices lie within that array. Find the maximum number between these two indices in less than O(N)

Multiply two numbers without using * and only be using bitwise operations

Display nodes of a tree in level order using DFS

Implement a deque using stacks

Given the entire dictionary of English words, what data structure will you use to efficiently store and match the custom regex string like "D*sk", where * represents any single alphabet, and return the list of matched words?

Given a skewed tree, an insect is sitting at the root of the tree at t = 0min, every minute insect steps down in the tree, find the probability of the insect being at any node at t = infinity. Once I came up with a solution various other complexities has been added to the problem such as: What if the tree is binary tree (written code for this) What if three is n-ary What if it is now a directed acyclic graph Handle cases that there can be more than one entry point There can be more that one way to reach a node

Given a binary tree of numbers and a search number has given, find out first occurence of that number and smallest distance from root node. if you have given k search numbers find their occurence and nearest from root node in a single walk.

Given a string of numbers put commas so that it become readable like million trillion thousands. eg 1010503 ===> 1,010,503

Given an array of 0s and 1s. find maximum no of consecutive 1s. If you have given chance to flip a bit to 1 such that it maximises the consecutive 1s. find out that flipped bit and after flipping that bit maximum no of consecutive 1s. Above question but you have options to flip k bits.

Design a system which will keep track of product and its inventory count. The service will expose two api incrCnt(int prodId, int cnt) and decrCnt(int prodId, int cnt). Which db would you use ? How will you handle hot products ?

Design a system in which read a file which has data and operation to be performed give a line by line. Ex a=5, next line b= 10, next line a*b. This design extended to support float, doubles, boolean, vector and complex numbers. Like if the file has a=5+i8, then how you handle such scenarios. How you will store and process data.

Design database schema with entity and relations to store the family tree of a person.

Given an integer array and an integer K, find the number of sub arrays in which all elements are less than K.

Follow up -
Given an integer array and an integer K, find the number of non overlapping unordered pairs of sub arrays in which all elements are less than K.

Design a low level design and db schema for railway reservation system for supporting following 2 features -

1) User would give source city, destination city and date as input and would get the list of trains matching the criteria.

2) On selection of a train from the list user should be able to see the schedule of the train including the arrival time, departure time and station name.

Design a distributed key-value store that can perform the following
Store a set of attributes (value) against a particular key (k)
Fetch the value stored against a particular key (k)
Delete a key (k)
- Perform a secondary index scan to fetch all key along with their attributes where one of the attribute values is v.
Key can have a value consisting of multiple attributes.
Each attribute will have name, type associated (primitive types - boolean, double, integer, string) & type has to be identified at run time.

Ex -
1) Key = delhi has 2 attributes ( pollution_level & population)
2) Key = jakarta has 3 attributes (latitude, longitude, pollution_level)
3) Key = bangalore has 4 attributes (extra - free_food)
4) Key = india has 2 attributes (capital & population)
5) Key = crocin has 2 attributes (category & manufacturer)

Example of Secondary index:
Get all keys (cities) where pollution_level is high. Get all medicines by manufacturer (GSK)
So, in a nutshell, value must be strongly typed when defined.

Attribute
1. Attribute is uniquely identified by its name (latitude, longitude etc.
2. Data type of the attribute is defined at the first insert. (i.e. data type of pollution_level is set when key = delhi is inserted)
3. Once data type is associated with a particular attribute, it cannot be changed.
(i.e. free_food when defined takes type = boolean, hence, any key when using the attribute - free_food must allow only boolean values on subsequent inserts/updates)

Non-functional requirements

Highly scalable - Support for high throughput with very low latency
Highly available
Shared nothing architecture i.e. Support for Multiple nodes and each node is independent & self-sufficient.
Stretch - Smart client i.e. clients being aware of available servers & makes smart routing based on that available information.

Design twitter trending topics feature to show trending topics in past 24 hours.

Given two very large files – first contains Id and name, another one contains Id and address – you need to create 3rd file which will contain id, name, and address. -First, ask the clarifying questions and then tell the approach.

Two tables employee (contains name and Id) and employee details having work experience history (contains Id, fromYear, toYear) – find out all the employees who worked w/o career break.
Java implementation for the same.
From the same table list the name, fromYear, toYear for all employee.
Dependency Injection.
Design patterns which can be used.

Given a binary matrix of size M * N. You are given H and V where H denotes the number of horizontal cuts and V represents number of vertical cuts. You need to find whether you can make H and V amount of cuts such that each submatrix formed after the cuts will have equal number of 1. E.g.

4 5
1 1 1 1 1
0 0 1 1 1
0 1 1 1 1
1 0 1 1 1
Given H=1 and V=3, we can make 1st horizontal cut after 2nd row and 3 vertical cuts after 2nd, 3rd and 4th column such that each of the sub matrix will have equal number of 1s.

| ----------------|
| 1 1 | 1 | 1 | 1 |
| 0 0 | 1 | 1 | 1 |
| ----------------|
| 0 1 | 1 | 1 | 1 |
| 1 0 | 1 | 1 | 1 |
| ----------------|

Given a remote having 0-9 digits, plus button (to increase channel), minus (to decrease) and previous channel button (to go to previous channel). We were given 2 numbers stating start and end channel number and an array having various channel numbers. The task is to go to all channel numbers given in array with minimum number of clicks.

You are given 2 arrays: one representing the time people arrive at a door and other representing the direction they want to go(in or out) You have to find at what time each person will use the door provided no 2 people can use the door at the same time. Constraints: the door starts with ‘in’ position, in case of a conflict(2 or more people trying to use the door at the same time), the direction previously used holds precedence. If there is no conflict whoever comes first uses the door. Also if no one uses the door, it reverts back to the starting ‘in’ position. Should be linear time complexity.

Implement auto complete for IDE, you will be given strings of classes and input, input can be like MVC, MoClick, MouseClickHand
For MouseClickH => MouseClickHandler

MVC => can match to any classes where first word starts from M then V then C

Make a system that returns the average number of hits on the site per minute from the past 5 minutes

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).

Design distributed crawling system which would be feeded a source url.

Given 'n' servers each having millions of sorted integers. Find distributed median of all the 'n' servers.

Given a binary matrix of 0 and 1 where we can move in 4 directions left, right, top, down and we can only pass through 1's. Find the shortest path from given source coordinate (a,b) to destination (m,n) given we can flip any one of the zero to one.

Implement a comparator class that is capable of sorting by multiple key/order pairs, each pair being a tiebreaker for the previous.

You're running a pool of servers where the servers are
numbered sequentially starting from 1. Over time, any
given server might explode, in which case its server
number is made available for reuse. When a new
server is launched, it should be given the lowest available number.

Write a function which, given the list of currently
allocated server numbers, returns the number of the next server to allocate.

For example, your function should behave something like the following:

>> next_server_number([5, 3, 1])
2
>> next_server_number([5, 4, 1, 2])
3
>> next_server_number([3, 2, 1])
4
>> next_server_number([2, 3])
1
>> next_server_number([])
1

Server names consist of an alphabetic host type (e.g. "apibox") concatenated with the server number,
with server numbers allocated as before (so "apibox1",
"apibox2", etc. are valid hostnames).

Write a name tracking class with two operations,
allocate(host_type) and deallocate(hostname).
The former should reserve and return the next
available hostname, while the latter should release
that hostname back into the pool.

# For example:
#
# >> tracker = Tracker.new()
# >> tracker.allocate("apibox")
# "apibox1"
# >> tracker.allocate("apibox")
# "apibox2"
# >> tracker.deallocate("apibox1")
# nil
# >> tracker.allocate("apibox")
# "apibox1"
# >> tracker.allocate("sitebox")
# "sitebox1"

Write a map implementation with a get function that lets you retrieve the value of a key at a particular time.
t:0 A =1
t:2 A = 2
get(A, t:1) -> 1
get(A, t:3) -> 2

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.

Implement BST Iterator and use them in 2 sum and 3 sums problem on a BST

Implement a rate limiter that multiple threads can use, while the global rate is limited to a value

Implement a thread-safe data structure which can keep track of number of incoming
requests grouped by IP Address over a time window. Add support for grouping by other
attributes such as BrowserAgent.

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)

Design DB schema for maintaining e-commerce various category ,sub category ,sub-sub category and so on.

Write a program to find number of words in a file not using any standard tokenizing API's.

Given n, you will be getting stream of sets each set may contain like (1,3,4,5) which signifies that 1,3,4,5 are related. Similarly you may get like (6,7) , (1,8).
And you will be asked to find whether 1 & 4 are related => Yes (as they are from same set).
3 & 8 are related => yes as 8 & 3 are related through 1.
5 & 7 are related =>No

Implement a fair mutex

An array is called a Good Array if the elements continually increasing or continually decreasing or continually decrease and then increase.
Question 1: He asked how will you tell whether a given array is a good array or not.
Question 2: Given an array, you are allowed to add any number of values to each of the element. Find the minimum sum of elements that can make the array a good array.

A software-based LRU Cache replacement algorithm has to be implemented for a Single Touch/Multi-Touch Cache. Single Touch can occupy at least 30% of the total cache space. A key accessed for the first time will appear in the Single Touch cache. When accessed multiple times, this will be part of the multi-touch cache. Also, multiple threads will access the cache. Following are the functions allowed for cache access.
1. get(key): returns the value against the key if present else return NULL
2. set(key, value): set the value against the key

Given a tree, and there will be treasure in one of the nodes. We can query any node, it will return the node itself if it contains the treasure or it returns the branch which leads to the treasure. we need to find out the treasure in minimum number of queries.

Design a jenkins kind of system

Imagine someone maliciously duplicated every file on your computer, and completely randomized their names and locations on your hard drive. Discuss an efficient way to clean up your drive of all these duplicates.

Two very very large files F1, F2 containing key, value pairs. Write these key, values to a third file without any duplicates.

Design real time tail log search

Build a key-value data structure that allows the user to take a snapshot of the data. The user can read the key-value store from any snapshot.

Structure has the normal key/value like methods plus something like
snapshot = dataStructure.takeSnapshot()
value = dataStructure.get(key, snapshot)
void dataStructure.deleteSnapshot()

A table has some number of balls at various positions on a line segment. All are moving with same speed in one or the other direction. Wherever a collision occurs they change direction. A ball falls from the edges of the table. Find the time when all balls fall of the table given initial position of each ball and speeds

Given a list L of video names and their watch rates, write a function that will return the videos with the top 10 watch rates. Video names may appear more than once.

Example:

L = [(‘abc’, 10), (‘def’, 15), (‘ghi’, 10), (‘abc’, 12), …, (‘xyz’, 100)]

The function should return [‘xyz’, ‘abc’, …, ‘def’, ‘ghi’]

Write a function that takes a list L and returns a random sublist of size N of that list. Assume that the indexes must be in increasing order. That is, you cannot go backwards.

Example:

L = [1, 2, 3, 4, 5]
N = 3

The function should return one of these lists:

[1, 2, 3]
[1, 2, 4]
[1, 2, 5]
[1, 3, 4]
[1, 3, 5]
[1, 4, 5]
[2, 3, 4]
[2, 3, 5]
[2, 4, 5]
[3, 4, 5]

Consider an undirected tree with N nodes, numbered from 1 to N. Each node has a label associated with it, which is an integer value. Different nodes can have the same label. Write a function that, given a zero indexed array A of length N, where A[j] is the label value of the (j + 1)-th node in the tree and a zero-indexed array E of length K = (N – 1) * 2 in which the edges of the tree are described, returns the length of the longest path such that all the nodes on that path have the same label. The length is the number of edges in that path.

Example:

A = [1, 1, 1, 2, 2]
E = [1, 2, 1, 3, 2, 4, 2, 5]

This tree is shown below. A node follows the form label, value.

----------1, 1

-----1, 2 1, 3

2, 4 2, 5
The function should return 2, because the longest path is 2->1->3, and there are 2 edges in this path.

Assume that 1 <= N <= 1000 and each element of the array A is an integer in the range [1, 1000000000].

Given a string A consisting of n characters and a string B consisting of m characters, write a function that will return the number of times A must be stated such that B is a substring of the repeated A. If B can never be a substring, return -1.

Example:
A = ‘abcd’
B = ‘cdabcdab’
The function should return 3 because after stating A 3 times, getting ‘abcdabcdabcd’, B is now a substring of A.

You can assume that n and m are integers in the range [1, 1000].

Given 1-D list of co-ordinates determine if interval (a,b) is covered

Ex - [(2,5), (5,7),(1,4)] and interval = (1,6)
return true
Explanation - Points 1 to 6 lies in list of interval given 1 to 4. 2 to 5 and 5 to 7.

[(1,4),(6,7),(2,5)] and interval - (1,6)
return false
Explanation - Distance between 5 to 6 is not covered in the list given so return false

Compare two documents(string array) based on n grams.
e.g doc1 – Today is Sunday.
doc2 – Today is Saturday
if n = 2 then number of duplicates is 1 (Today is)
if n = 1 then number of duplicates is (Today, is)
if n = 3 duplicates is 0

Given a bench with n seats and few people sitting, tell the seat number each time when a new person goes to sit on the bench such that his distance from others is maximum

Given a room with thief on left side of the room with finite number of sensors. He has to reach on right side missing the sensors. Each sensor is placed at any random point in the room and has its coverage in the radius r. Find out if the thief can reach to the right side without touching the range of any sensor.

Given an infinite chessboard, find minimum no. of steps for a knight to reach from the origin to (x, y).
Extension A list of forbidden coordinates are introduced where knight can’t reach. Handle this in your code. Make sure the infinite loop is handled since the board is infinite.

Given a matrix of people(denoted by small alphabets) and bikes(denoted by capital alphabets), find the nearest bike for a given person.
How will you change your solution if you have to find bikes for a set of people? (assuming multiple bikes can be at the same distance from 1 person)

Given an array of n integers, find the lexicographically smallest subsequence of length k.

Given a list of player names and their scores – {Carl, 70; Alex, 55; Isla, 40}, design a data structure that can support following modules in optimal time-
i) updateEntry(string name)
ii) getEntryFromRank(int rank)

Given an input stream of boolean values, design a data structure that can support following modules in optimal time-
i) setTrue(index)
ii) setFalse(index)
iii) setAllTrue()
iv) setAllFalse()
v) getIndex(index)

Given two strings, A and B, of equal length, find whether it is possible to cut both strings at a common point such that the first part of A and the second part of B form a palindrome.

Extension1. How would you change your solution if the strings could be cut at any point (not just a common point)?
Extension2. Multiple cuts in the strings (substrings to form a palindrome)? Form a palindrome using a substring from both strings. What is its time complexity?

Given a stream of integers, a value k and a value w, consider the integers in the window w and chop off greater k and smaller k elements from the window w. From the remaining elements, compute the average.

Implement the version control map system which takes the snapshot of the versions of data. Implement the following functions:

put(key, value) -> puts the value again the key in the latest version of the map

get(key) -> get the value of the key for the latest version of the data

snapshot() -> take a snapshot and increment the version

getValVersion(version id, key) -> return value of the key of the particular version

Given various subsequences of an array, print the overall array:

Example: [1, 3, 5], [1, 3, 9], [9, 5]

Array : [1, 3, 9, 5]

A graph has N vertices numbered from 1 to N. We have two lists. One list M consisted of edges between vertices. The other list K consists of restricted paths. We have to add edges one by one from M and check whether the addition of the particular edge leads to a path between the restricted edges given in K. If it creates a path, we have to discard the edge.

Example: N = 4; K = {(1, 4)}; M = {(1, 2), (2, 3), (3, 4)}. Here, addition of edge (3, 4) will create a path between 1 and 4. Hence we discard edge (3, 4)

You are given 2 strings which are exactly same but 1 string has an extra character. Find that character.

You are given an array of million numbers and provided a range of index (say left, right). For multiple queries, each with input left and right indexes, output the maximum in that range.

Given (x, y) coordinates, create a function such that each coordinate is uniquely mapped to an integer. Also make sure that given an integer, you should be able to find (x, y) coordinates. So F(x, y) = z and also that inverse F(z) = (x, y).

We have to paint n boards of length {A1, A2…An}. There are k painters available and each takes 1 unit time to paint 1 unit of board. The problem is to find the minimum time to get
this job done under the constraints that any painter will only paint continuous sections of boards, say board {2, 3, 4} or only board {1} or nothing but not board {2, 4, 5}.

Input : k = 2, A = {10, 10, 10, 10}
Output : 20.
Here we can divide the boards into 2
equal sized partitions, so each painter
gets 20 units of board and the total
time taken is 20.

Input : k = 2, A = {10, 20, 30, 40}
Output : 60.
Here we can divide first 3 boards for
one painter and the last board for
second painter.

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

Find 'k' largest element in stream of integers.

Constraints -
1) k can vary for every query
2) Stream can not be stored

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 directory change command -

cd a/b/../c/d/e/../../

Output the visit count for each directory such as -
Root - 1
a - 2
b - 1
c - 2
d - 2
e - 1

Given range of routing numbers, determine which bank it belongs to.

Ex-
I/p -(123400,123500, BOA), (12538, 12548, GCU)…

For 123450 - Output BOA
12540 - Output GCU

Given multiple tuples in the form of (A,B) where A is the parent and B is the child in a binary tree, find if the input is valid or not. 4 error conditions were provided:
1. If a parent has more than 2 children,
2. If duplicate tuples entered,
3. If the tree has a cycle,
4. If more than one root possible.

For violation of multiple validity conditions, print the condition coming first in the above order.
If the input is valid, print the tree in a serial representation. For eg: If input is (A,B), (B,C), (A,D), (C,E) , output: (A(B(C(E)))(D))

Design a catalog system – Restaurants, Items, Categories, VariantGroups like Size, Variants like (S,M,L), AddOnGroups like Extra cheese, AddOns like White Cheese, Yellow Cheese. Price of item will vary on variant selected and even addon price will vary on variant selected.

Design Flipkart Flash sale architecture. 2 million hits and 20k orders in 2 sec.

Given character a-z find out nth permutation. Where all permutation are only ascending. For e.g

Given characters a,b,c. valid permutations are : a,b,c,aa,ab,ac,bb,bc,cc,aaa,aab,aac,abb,acc,baa,bab,bac,bbb,bbc,bcc,caa,cab,cac,cbb,cbc,ccc

Ex- 4th permutation is : aa

Given customer Geo Location(Lat-Long) and List of Restaurants. Each restaurant consist of :

- Lat long of restaurant
- Name
- List of Items, where each item has
- Item Name
- Prep Time
- Sensitivity ( Low, Medium, High). Lower sensitive items like Icecream cannot be delivered more than 2 KM.

- Find out List of Restaurant Given Customer and Cart is Empty
- Find out SLA(Time to deliver) given cart, restaurant and Cutomer
- Parameters should be Configurable like Sensitivity, Max prep time etc

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

You are given an N-Dimensional list with 2 methods:
i) getDim -> returns the dimensions .e.g [5,4,3].
ii) getElement([i,j,k]) -> return list[i][j][k] . You have to implement a method to sum all elements in the list.

Given a list of files. Return all the unique lines from all files.

Given a set of points, find the smallest rectangle by area.

Given N shop coordinates on a 2-d plane, Find the nearest shop from a man whose coordinates are given.

Give you a text file, remove duplicated lines.

A string consists of ‘0’, ‘1’ and '?'. The question mark can be either '0' or '1'. Find all possible combinations for a string.

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.

Given unsorted array, find how many elements can be found using binary search
- ex : [5,4,6,2,8] -> Ans : 3 -> '6' and '8' and '5' can be found using binary search

Implement an api that let's users create multiple timers. You can only use one system timer in your implementation though. For example a user can write:

timer.startTimer(3, callback)
timer.startTimer(7, callback)
timer.startTimer(1, callback)

and the user will get three callbacks 1, 3, and 7 seconds later. In startTimer you only have one timer that you call like this:

System.startTimer(seconds, callback)

but it can only be called once it has finished with the previous timer.

Brace Expansion
Given a string, perfrom the brace expansion
For example,
Input: s = "a{d,c,b}e"
output: {ade , ace , abe}

Given a rectangle with width 'W' and height 'H', you have to fit a string 'S' in it with maximum possible font size
The font size ranges from 1 to 30
You are given two APIs getCharacterWidth(char c , int font_size) and getCharacterHeight(int font_size)
getCharacterWidth(char c , int font_size): returns the width of a character for a particular font size
getCharacterHeight(int font_size): returns the height of characters for a particular font size

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

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.

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

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?

Explain the Data Structure which is well suited to implement UNIX commands like PWD, LS, MKDIR, CD in an imaginary OS. No code required.

Unsorted array and a position ‘P’. Return the element that is likely to come to the given location upon sorting the array. TC in O(n).

A thief trying to escape from a jail has to cross ‘N’ walls each with varying heights. He climbs ‘X’ feet every time. But, due to the slippery nature of those walls, every times he slips back by ‘Y’ feet. Now the input is given as (N, {H1, H2, H3,….Hn}, X, Y}. Calculate the total number of jumps required to cross all walls and escape from the jail.

Singleton Design pattern. How you make it double ton(in even call of getInstance() first object should be return and odd call of getInstance() second instance should be return). Make it triple ton.

Print series 010203040506. Using multi-threading 1st thread will print only 0 2nd thread will print only even numbers and 3rd thread print only odd numbers.

Add a digit to a number that is represented by a linked list, where each node is a digit of the number. The linked list couldn’t be modified, except the digits to be modified in answer and the number could be infinitely long. Need to do it in O(1) space.

Find the Minimum length Unsorted Subarray, sorting which makes the complete array sorted

Maximum difference between node and its ancestor in Binary Tree in O(n) time.

Given a very large binary number which cannot be stored in a variable, determine the remainder of the decimal equivalent of the binary number when divided by 3. Then generalize to remainder of any number 'k'

Given a pre-order traversal, construct a binary search tree in O(n) time.

Given a large text file, find an efficient algorithm to find the least distance(measured in number of words) between any two given words.

here are tuples given for each users of a website (Si,Ei) where Si denotes the when the user entered the website and Ei denotes when the user exits the website .Find the maximum number of users active of website at any time duration.

There is a binary stream coming . You need to print true or false based on the fact whether the number formed is divisible by 5 or not.

You are given a text file. You have to return the list of starting index of the given word in text file. Design an efficient DS for that.

Example :-
Text file content : “geeks for geeks”
word : “geeks”
List : {0,10}

In a file, there are two columns, first column has some word (String) and 2nd column has some value (Double).
Example :-
ABC 23.4
ERF 34.89
WERT 122.9

Now user wants some arithmetic operations like
1) ABC + ERF = 23.4 + 34.89 = 58.29
2) ABC – WERT = 23.4 – 122.9 = -99.5

Design an efficient DS for these kind of operations.

Given a remote having 0-9 digits, plus button (to increase channel), minus (to decrease) and previous channel button (to go to previous channel). We were given 2 numbers stating start and end channel number and an array having various channel numbers. The task was to go to all channel numbers given in array with minimum number of clicks.

Given MxN binary matrix, find the largest sub-square matrix with all 1’s.

Design a geographically partitioned multi-player card game, that supports multiple players, multiple games at a time.
Each game will have one contractor like ones we have in a bar, He can play a game or just watch it. Integrate payment systems.
First HLD was required, use cases, flow diagram. then a low level design was required all necessary classes where will you use polymorphism, where inheritance, multithreading, synchronised approach if needed, socket connections

Design a Netflix type system. Start from HLD to LLD.
Consider requirements like search, video serving, authentication, security, serving multi quality video.

Given an array of integers. We need to answer two types of queries point update and range sum in minimum time.

Put the given random pointers in linkedlist to point to next greater node such that if you transverse the list using random pointers, list become sorted. duplicates are allowed.

Find third highest value in a binary tree

There are n Thread , n/2 thread are producer and n/2 are consumer, number produced by producer-1 thread must be consumed by consumer-1 thread. Thread must also run in order, producer 1, then consumer 1, again producer 2 and then consumer 2…so on…..

Implement function which add n days to given date without using inbuilt library.

Given data of millions of people, (name, age, M/F etc.) Develop an API that will have age range as input and yield the count of people under this range as output.

A T20 match is going on. You’re in Team B. First innings is over, they have scored “teamARuns” runs. Your team has scored “teamBRuns” runs at the end of “balls” balls. A ball can have multiple possibilities like [0, 1, 2, 3, 4, 5, 6, Wicket, No ball, Wide ball]. What is the probability that your team (Team B) will win?

Given a dictionary of words and a string pattern. Output the count of words that match the string pattern in the dictionary.
Eg. Dictionary: [cat, rat, mat, apple, boy, bat]
String pattern: ?at
Output: 4 (because cat, rat, mat, bat matches the string pattern)

Given any two nodes in a binary tree, find the path from 1st node to another, and tell if the path is a straight line, or there are turns on the line, find number of turns.

Find the maximum difference between any combination of child and parent node in a given binary tree. Here child node can be any level below parent node, but should be in the same sub tree starting from parent node.

Design Truecaller. Both HLD and LLD.

Given a chessboard, find minimum number of moves for a knight to reach from source to destination.

Given a fully connected graph with n nodes and corresponding values. One node can interact with other node at a time, to replace/ignore/add its value to other node’s value. Assuming this operation takes 1 unit of time, how much time would it take for all the nodes to have value equal to sum of all the nodes.
Examples : Given a graph with values {1,2,3,4}, find total time it takes, such that all nodes have value as 10.

Given a Singly Linked list, Update the second half of the list such that n-th element becomes sum(1st + nth) element, (n-1)st element becomes sum(2nd + n-1st) element and so on. Eg: 2->3->4->5->6 => 2->3->(4+4)->(5+3)->(6+2)

There are some professors, some courses, and some students.
Each professor can teach only a single course.
Each course has a fixed duration(Eg. 10 weeks).
For each professor, you are given time availability schedule(assume week wise).
Each student has a list of courses he wants to learn.
There can be only 1:1 classes, i.e., 1 professor can teach only a single student.
A student can attend only one course at a time.
A professor has to finish teaching a course in a one go.

Your aim is to prepare a schedule so that all courses are taught in the least time.

Given a stream of numbers which contains n numbers, each number is positioned at max k positions away from its actual position. Sort the array in the most optimized way.

Implement a queue using only one stack.

It’s a two player game. Both the players are equally intelligent to win the game. Give n no. of stones. A player can choose either 1 stone or k stones or l stone (1<k<l). Suppose player 'A' starts game then challenge was to identify the player who will win the game. Player who picks the last 1 stone or last k stone or last l stones win the game.

Design bus booking system:- Each row has x seat. If customer wants K seats if you have K consecutive seats available, reserve them. Otherwise give seats from any row.

There is a bridge and N no. people takes (a1,a2,—an) time to cross it and there are K torch and at any time x no of people can pass the bridge and it takes maximum of x people time to cross it. Minimum time required for N persons to cross the bridge.

There is a graph where each node represents a city and it contains specific no. of people. A tournament is going on and each match is playing in one city. All city’s people gather to watch match. Traffic department wants to manage how many people travel through city x if match is playing in city y for each x. City x and y can be any city.

Given an Infinite stream of strings as AAAAABBBCCDDDEEE… How will you arrange characters so that string become unique without duplicates .

Return true if it is possible to arrange else return -1.

Ex . AAABBCCDEF – O/p ABABCDCEF : Possible . AAAAAAAAAAAAAAAAAAAAAAB : Not possible

Given an array of integers, replace every number with the next higher number to its right. If a number can’t be replaced, we leave it as-it is.
For example, the list: 5, 2, 1, 4, 6, 7 needs to be changed to 6, 4, 4, 6, 7, 7.

Given two unsorted arrays A, B. They can contain duplicates. For each element in A count elements less than or equal to it in array B

Examples:

Input : A = [1, 2, 3, 4, 7, 9]
B = [0, 1, 2, 1, 1, 4]
Output : [4, 5, 5, 6, 6, 6]

Design a mall where there are 'm' entry gates and 'n' exit gates. There can be only 'x' number of people inside it. No more then 'x' people can be inside mall at any time.

Design a movie ticket booking system like bookmyshow.com

Follow-up question -
1) How do you handle issues like scalability, concurrency, fault-tolerance etc.
2) Show movie theaters near to user where movie is playing and seats are available
3) Design database. What kind of DB would you use SQL or No-SQL
4) In real time how would you show which seats are booked which are free
5) If theaters do not have any api for fetching information then what can we do about it.

Design Uber. Low level Design needed (OOPS based - classes, relations, message flow etc.)

Design Cricinfo website

Design snake n ladder game to be played online

Design a system having multiple jobs, interacting with each other such that :
1) A job can run for very long periods (1-2 days)
2) A node can fail/crash on which certain job is running
system should be scalable
3) Amount of data getting transferred is huge
4) Data in the system is very sensitive and needs security
job/s can fail

Top View of a Binary Tree in constant space

Given a pattern containing only Is and Ds. I for increasing and D for decreasing. Devise an algorithm to print the MINIMUM number following that pattern. Digits from 1-9 and digits can’t repeat.

Example:
1. Input: D Output: 21
2. Input: I Output: 12
3. Input: DD Output: 321
4. Input: II Output: 123
5. Input: DIDI Output: 21435
6. Input: IIDDD Output: 126543
7. Input: DDIDDIID Output: 321654798

Implement ConcurrentHashMap class in Java

Implement LinkedHashMap class in Java

You have been given a grid with some doors, walls and some empty spaces.
1st part : You have to tell the least no of moves to go from random position in the grid to the nearest door. You can move in four directions only, i.e, left, right, above, below.
2nd part : Least distance of every empty cell to the nearest door. Lots of discussion was done on both the parts of the problem.

Design garbage collector in Java

Maximum triangle path Sum : Starting from the top of a pyramid of numbers like below, you can walk down going one step on the right or on the left, until you reach the bottom row:
55
94 48
95 30 96
77 71 26 67

One of such walks is 55 -> 94 >- 30 -> 26. You can compute the total of the numbers you have seen in such walk, in this case it’s 205.

Your problem is to find the maximum total among all possible paths from the top to the bottom row of the triangle. In the little example above it’s 321.

Design a online shipment tracking system.

Design a system to upload images and tag them. Ability to search images with single and multiple tags.

Given a very large binary number which cannot be stored in a variable, determine the remainder of the decimal equivalent of the binary number when divided by 3. Generalize to find the remainder for any number k.

Given a file having many lines of text(words) and given a dictionary having an API function boolean isValid(String word), which will return true is a word passed to this function is valid word in dic.,and will return false if given passed argument is not a valid word in dic.

Now read the file and check if each word as well as all possible words from its L to R and R to L combinations, are valid words in dic. or not.

Given sequentially placed boxes, each representing a number( which may be positive or negative), we need to select the numbers in order to have the maximum sum, having the constraint that if we select a given box, we cannot select adjacent box to it, but can select any other.

Given 2 integers, add them without using any arithmetic operator

Implement a LRU cache with ttl at each block

Given some resources in the form of linked list you have to delete all the resources which sum up to 0(Zero) and return the remaining list.

Find all anagrams of a given string in a file of size 1TB.

Given two strings print all possible permutations of two strings such that the order of characters are maintained.

Given an array,generate all valid ip address from the array.

Find Longest Repeated Substring in the given string.

Given a equi-weighted uni directed graph and need to find the max distance possible from a given node.