## SDE-2 Interview Questions

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Implement a Message Broker, with Publisher and Subscriber. There can be multiple Topic or Subject in Message Broker.

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Implement Thread safe timer with start, stop and reset functionality.

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Find K which decides the number of open brackets are equal to the number of closed brackets.

input : (())

output : 2

Reason : if we divide the string at 2nd position, we get two open brackets and two closing brackets, and they are same .

input : (())))(

output : 4

Reason : if we divide the string(not necessarily equally) at 4rth position, we have (()) on the left side and on the right side we have ))( , as you can see, on the left half, we have two opening brackets and on the right half we have two closing brackets and they are equal .

input : ))

output : 2

Reason : there is no open brackets , so if we divide taking the whole string's length, we have )) on the left half and nothing on the right half. Now you can see that on the left half there is no open brackets and on the right half there is no closed brackets.

This question should be clear by now and remember you have to find out that K .

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Find the Maximum number of distinct nodes in a binary tree path

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find the given Binary tree is mirrored tree or not

should be like

60

/ \

30 30

/ \ / \

20 50 50 20

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Given a BST (Binary Search Tree) , Each node value should replace with sum of the node which are greater-than the given node.

conditions :

No Extra space / variable can use

Modify the existing tree in optimal way.

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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.

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Design a online shipment tracking system.

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Add 1 to the integer represented by a linked list with O(n) time, O(1) space, no recursion(stack space) and without reversing the linked list.

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Design an OOP concept for an application where employee can dispatch their incoming phone call according to their seniority level if they are not able to solve.

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Design a kind of kindle fire application where we can subscribe news channel and read the news from all publishers as a digital format.

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Write a program to check whether it is a valid binary tree or not.

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Multiply two numbers represented as a linked list.

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A ‘plus’ pattern of size 1 is defined as following :

1

1 1 1

1

size 2 :

1

1

1 1 1

1

1

Find size of largest plus pattern in given 2D matrix which has only 0s &1s.

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Given a sorted array which has been rotated n number of times. Find the value of n.

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Clone the binary tree.

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Return the maximum length sequence containing consecutive numbers from a binary tree.

90

/ \

1 66

/ \

2 67

/ \ /

5 4 68

/ \

99 100

Consecutive sequence of maximum length: [66, 67, 68] of length 3.

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Implement Tower of Hanoi without using recursion.

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A stepping number is defined as a number in which the absolute difference between the consecutive digits is not greater than 1, A stepping number cannot be a single digit number. You have to find the number of stepping numbers between n1 and n2 where n2 > n1 and n2, n1 > 0.

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Given a stack of integers of size n, you have to sort it using only push and pop operations in O(1) space.

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Given a tree return the number of elements for the level with the maximum elements.

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Given an array it can be of 4 types

(a) Ascending

(b) Descending

(c) Ascending Rotated

(d) Descending Rotated

Find out which kind of array it is

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Design a conference room booking system for a company which can have offices in multiple cities, each city can have multiple buildings, each building can have multiple floors, each floor can have multiple rooms. Each room can have features like capacitiy, video conferencing available, etc.

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Design a kind of kindle fire application where we can subscribe news channel and read the news from all publishers as a digital format.

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You are given a String S of length N. Now, a good subsequence is one that can be represented in the form (a raised to the power i) (b raised to the power j) (c raised to the power k) where i≥1, j≥1 and k≥1. For example ,if i=2, j=1, k=3, it represents the string aabccc. In short, a good subsequence is a subsequence that first consist of

i ′a′ characters, followed by j ′b′ characters, followed by k′c′ characters, where i≥1, j≥1 and k≥1

Now, you need to find the number of good subsequences of String S. As the number of such subsequences could be rather large, print the answer Modulo

(10 raised to the power 9) + 7.

Note: Two subsequences are considered different if the set of array indexes picked for the 2 subsequences are different.

Input : abcabc

Output : 7

Explanation

Valid sub sequences are(1-based indexing):

{1,2,3}

{1,2,6}

{1,5,6}

{4,5,6}

{1,2,5,6}

{1,4,5,6}

{1,2,3,6}

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I need to create a database that have five columns each entry is such that there can be repeated tuples in each column(No primary key).There will be no two same entries

There are 5 Methods that needs to be implemented

1. Create() - create the database

2. Add(string a,b,c,d,e) - Add single entries with 5 tuples(all strings)

3. Update (culumntype1, columnvalue1,culumntype2, columnvalue2)

- each entry having culumntype1 = columnvalue1 will be updated by columntype2=columnvalue2 and return total such eantries.

4. Delete (culumntype1, columnvalue1)

- each entry having culumntype1 = columnvalue1 will be deleted.and return total such eantries.

5. Search(culumntype1, columnvalue1)

- Search each entry having culumntype1 = columnvalue1 and return total such eantries.

How to implement in best possible way such that there can be 50,000 such entries?

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how to create an object on the stack.

and also make sure that only 5 objects are created for the class

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Design Amazon Recommendations Feature. Focus on designing how would you store and make it accessible fast? What would be class design like for the class which would provide list of products which people bought similar to a given product? How would you test that class?

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Give a large multi MB byte file in memory, a system handles delete requests for segments typically of the order of bytes. The system has a constraint that individual purge requests of byte segments are expensive, so that the no. of purges are a minimum.

Eg. a 5 MB file receives delete requests for offsets (1, 100), (250, 550),(1000, 1200), (400, 600), (800, 900), (1100, 1150)

Effective delete requests - (1, 100) , (250, 600), (800, 900), (1000, 1200)

The users of the system always go by the absolute byte ordering of the file. Eg. if byte 1 is deleted, the users of the system will reference the actual byte 2 as byte 2.

What data structure would you use to store these intervals such that the following operations are efficient 1. Looking up an interval 2. Inserting a new interval that has no overlap with existing ones 3. Inserting a new interval that has partial overlaps with existing intervals. This would involve collapsing the existing intervals with the new interval to form a single large interval. Eg. Interval cache: {(1, 100), (250, 550), (1000, 1200)} , new interval : (400, 700) -> Interval cache: {(1,100), (250, 700), (1000, 1200)}

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Given an mXn Sorted matrix and a value X. Every row is sorted and first number of every row is greater than last number of previous row Find the value X in most efficient way.