## Practo Interview Questions

- 2of 2 votes

AnswersMaximum Sum of Building Speed

- uppubhai December 04, 2017 in India

You are the king of Pensville where you have 2N workers.

All workers will be grouped in association of size 2,so a total of N associations have to be formed.

The building speed of the ith worker is Ai.

To make an association, you pick up 2N workers. Let the minimum building speed between both workers be x, then the association has the resultant building speed x.

You have to print the maximum value possible of the sum of building speeds of N associations if you make the associations optimally.

Constraints

1≤N≤5∗10 ^4

1≤Ai≤10^4

Input

First line contains an integer N, representing the number of associations to be made.

Next line contains 2N space separated integers, denoting the building speeds of 2N workers.

Output

Print the maximum value possible of the sum of building speeds of all the associations.

Sample Input

2

1 3 1 2

Sample Output

3| Report Duplicate | Flag | PURGE

Practo SDE1 Algorithm - 0of 0 votes

AnswersWrite a Code

- ruchitraj93 February 14, 2017 in India

Steve is going to throw a party at his place tonight.He needs to visit two shops near his home-the first shop is d1 meters away from his place,the second shop is d2 meters away from his place, and there are d3 meters between these two shops.Calculate the minimum distance he needs to walk to visit both both shops and return back home. Steve always start from his palce.He can only travel using these 3 routes.HE can use any route any amount of time necessary,the only thing he needs to achieve is the minimum distance.

Find the minimum distance Steve has to walk to visit both shops and return home.

input: 1,1,1

output: 4

input: 10,20,30

output: 60| Report Duplicate | Flag | PURGE

Practo Software Developer Java - 0of 0 votes

AnswersGiven a list of list of positive integers, find all pairs of list which are having more than 3 elements overlapping.

- rohitatiit January 10, 2017 in India

What is the complexity.| Report Duplicate | Flag | PURGE

Practo SDE-2 Algorithm - 0of 0 votes

AnswersWedding Planner

- rayasamharish October 04, 2015 in India

Julia is a wedding planner who puts together phantasmagorical

extravaganza packages for new couples and their guests from 2 to

2,000. Hundreds of items are needed for each event, and Julia has a list

of supplier offers for all these items in various quantities. The price per

unit of every item is highly variable, depending on the supplier, the

number ordered, and the client/buyer who places the order. With her

years of record-keeping, Julia knows the best unit price she can get for

any item in any of a limited number of order sizes. Some items cost less

per unit when the number ordered goes up, some cost less per unit

when the number ordered goes down, and others have no rhyme or

reason for the unit prices available.

To price a new event, Julia consults her database of past offers.

If the amount needed for the new event is exactly the same as the

amount in a past offer, the unit price is also the same.

If she has a price for a higher amount and a price for a smaller

amount, her best guess will be that the unit cost will be linearly

interpolated from the unit costs for the closest lower amount and

the closest higher amount.

If the database only has one amount, then her best guess is that this

will be her unit cost.

And, if the amounts for which she has offers are all smaller or all

larger than the amount she needs, then she finds it most accurate to

linearly extrapolate from the closest two points to the amount

needed.

Finally, sometimes price offers lapse. When this happens, Julia, who

is not very database savvy, just overwrites the old unit price with a

zero or negative number. The amounts associated with zero or

negative unit price need to be disregarded.

automated so she can do it for hundreds of items with thousands of

individual prices.

Complete the function extrapolate , which takes a new amount n, an

array amount of old offer amounts in increasing order, and an array

ucost of corresponding unit prices. Your completed function should give

the expected unit price p for the new amount. The unit prices may

increase, decrease or oscillate, and may also contain invalid values like

0 or negative numbers. Your answer, as well as the unit prices in the

second array, should all be real numbers with exactly two decimal

places, representing dollars and cents. Use standard rounding to arrive

at two decimal places.

Input

A positive integer n, denoting the number if items for which a unit

price is needed.

1.

An array amount of l positive integers denoting the different order

amounts for which historical unit costs exist.

2.

An array ucost of l strings of real numbers denoting the different

unit costs for the corresponding amounts in array a.

3.

Output

A single positive number p with exactly two decimal places.

Note that the code for processing input and output is already present in

the system and designed to be compatible with the test case files used

to score your solution. There is no need to change only of the code other

than the body of the function extrapolate.

Constraints

1 ≤ l ≤ 100

2 ≤ n <= 2000

size(a) = l = size(u)

a(i) < a(j) ⇔ i < j

1

2

3

4

5

n = 25

a = {10, 25, 50, 100, 500 }

u = {"2.46","2.58", "2", "2.25", "3" }

Sample Output #1:

p = 2.58

Explanation #1:

The amount 25 is one of the values in the database. Its corresponding

unit price is 2.58.

Sample Input #2:

n = 2000

a = {10, 25, 50, 100, 500 }

u = {"27.32", "23.13", "21.25", "18.00", "15.50"}

Sample Output #2:

6.13

Explanation #2:

The item count 2,000 is not in the database. It is larger than any amount

in the database. The closest two price points to it are 15.5 for 500 and

18.00 for 100. Linear extrapolation from these two points means

reducing the price by 2.5 for every increase in amount of 400. There 3.75

jumps of 400 from 500 to 2,000, or 4.75 jumps of 400 from 100 to

2,000. The unit price for 2,000 is therefore 15.5 - 2.5 × 3.75 or 18 - 2.5 ×

4.75. Both expressions evaluate to 6.125. This rounds up to 6.13.| Report Duplicate | Flag | PURGE

Practo SDE1 - 0of 0 votes

AnswersStrong relation group

- rayasamharish October 04, 2015 in India

A group of social network experts are searching for an algorithm to find

"Strong relation groups" among people. A group of people form a strong

relation group if each of them know everyone else in the group. The

problem seemed very tough to them, so they want to attack a smaller

problem. If there are n people in a network and there are m pairs of

relationship among them, what will be the minimum size of the largest

"Strong relation group" in the network? If you know about graphs, you

can think of people as nodes and their relationship as edges.

Parameters:

Complete a function strongRelation which takes two integers n and m

as parameters.

Input Format:

First line contains a single integer denoting N.

Second line contains a single integer denoting M.

Return value:

Return the answer to the problem.

Constraints

1 <= T <= 100000

2 <= N <= 10000

1 <= M <= N*(N-1)/2

Sample Input:

3

2

Sample Output 1:

2

Sample input 2:

4

6

Sample Output 2:

4

Sample input 3:

5

7

Sample Output 3:

3

Explanation

1

2

3

4

5

"Strong relation group" cannot be smaller than 4.

For the third sample, it is easy to verify that any graph with 5 nodes and

7 edges will surely have a "Strong relation groups" of size 3 or more| Report Duplicate | Flag | PURGE

Practo SDE1 - 0of 0 votes

AnswersCan you predict the missing

- rayasamharish October 04, 2015 in India

grade?

Problem Statement

Introduction

The CBSE Class 12 examination, is taken by Indian high school students

at the end of K-12 school education. The scores or grades in this

examination form the basis of their entry to the College or University

system, for an undergraduate program. At the K-12 level, students

appear for examination in five subjects. These five subjects generally

include one language; three elective subjects oriented towards Science,

Commerce or Humanities; and any elective of their choice as a fifth

subject.

The Challenge

This challenge is based on real school data of the CBSE Class 12

examination conducted in the year 2013. You are given the grades

obtained by students with specific but popular combinations of subjects

(and all these students had opted for Mathematics). Their grades in four

subjects are known to you. However their grade in Mathematics (i.e, the

fifth subject) is hidden.

The records provided to you are the grades obtained by students who

had opted for the following combinations of subjects or courses and

obtained a passing grade in each subject. The individual subjects in the

data are:

English, Physics, Chemistry, Mathematics, Computer Science, Biology,

Physical Education, Economics, Accountancy and Business Studies.

The most dominant subject combinations, account for approximately

99% of the data are:

English, Physics, Chemistry, Mathematics, Physical Education

English, Physics, Chemistry, Mathematics, Economics

English, Physics, Chemistry, Mathematics, Biology

English, Economics, Accountancy, Mathematics, Business Studie

s

The grades of students in four subjects (other than Mathematics) are

provided to you. Can you predict what grade they had obtained in

Mathematics?

To help you build a prediction engine, we will provide you with a training

file, containing the grade points obtained by students with the above

subject combinations, in all five subjects.

Notes about the Grading System

The student is first assessed on a scale of 100. (S)He needs a score of at

least 33% to pass in the subject. Among those who pass:

Grade 1 is assigned to the top one-eighth of students who pas

s the course.

Grade 2 is assigned to the next one-eighth of students who pa

ss the course.

.....

Grade 8 is assigned to the last one-eighth of students who pa

ss the course.

If more than 1 student share the same score and lie in the margin, they

share the higher grade.

Input Format

The first line will be an integer N. N lines follow each line being a valid

JSON object. The following fields of raw data are given in json.

SerialNumber (Numeric): The identifier of the student record.

This is provided just for identification purposes and does n

ot have any direct use.

English (numeric) : The grade (between 1 and 8) obtained in E

nglish. This will always be present.

Three more numeric fields from among: Physics, Chemistry, Com

puterScience, Hindi, Biology, PhysicalEducation, Economics, A

1

2

3

4

5

The input for each record has the grade for all subjects opted by a

student, other than Mathematics which you have to predict as the

answer.

Constraints

1 <= N <= 10

The SerialNumber field will contain a unique numeric identifier such

that 1 <= SerialNumber <= 5 * 10 .

All other fields in the JSON fragment will represent the grades obtained

in four subjects and will be populated by numeric values between 1 and

8, both inclusive.

Output Format

For each student record that is given as a JSON object, containing the

grade obtained in four subjects, output the predicted grade in

Mathematics (this will be a numeral between 1 and 8, both inclusive) in

a newline.

Training File and Sample Tests

The training file with sample test data is available here.

The three files in this package are:

training.json

sample-test.in.json

sample-test.out.json

Training data as well as sample testcases have been provided in the

above file for offline training and to help you build your prediction

model. Feel free to include file data inside your code.

Sample Input

12345

{"SerialNumber":1,"English":1,"Physics":2,"Chemistry":3,"Comp

uterScience":2}

json_object

json_object

json_object

.

.

.

5

5

1

2

3

4

5

Sample Output

1

3

4

7

8

....

....

....

Explanation

It is predicted that first candidate obtained grade 1 in Mathematics, the

second candidate achieved grade 3 in Mathematics, the third candidate

achieved grade 4 in Mathematics and so on.

Scoring

For each of the N records in the input file, we will compute:

p = abs(Predicted Grade Point in Mathematics - Actual Grade Point in

Mathematics)

Where 'abs' indicates the Absolute Value or Magnitude. If p = 0 or 1 your

answer for that particular student record will be considered correct. i.e,

we allow a tolerance of one grade point away from the correct answer,

to take into consideration the marginal errors which might occur during

the testing or grading process.

Score = 100 * ((C-W)/N)

Where C = Number of Correct predictions, not more than one grade

point away from the actual grade point assigned.

W = Number of wrong (incorrect) predictions and

N = Total number of records in the input.

While the contest is in progress, only the score based on the sample

test case will be displayed to you. After the contest is completed, we

will revise the scores based on performance on a hidden test set only.

However, when you make submissions, you will be able to see whether

your program attains a positive score on both the sample and the

hidden test cases (to avoid a situation where unexpected errors occur

on the hidden test set at the end).| Report Duplicate | Flag | PURGE

Practo SDE1 - 0of 0 votes

AnswersNuclear Rods

- rayasamharish October 04, 2015 in India

A core meltdown has occurred at the Fubaru nuclear plant. There are

n nuclear fuel rods that are damaged and need to be removed using

specialized radiation-hardened robotic equipment

with solid-lead isolation chambers. Remote imaging has already

uniquely identified every damaged fuel rod and assigned it a number

between 1 and n. The imaging data also records which fuel rods were

fused to each other during the meltdown. Every recovery sortie by the

robot can pick up one set of nuclear fuel rods that are directly or

indirectly fused to each other.

The recovery costs per sortie are proportional to the square root of the

number of fused rods recovered. So the cost is K to recover K rods.

Isolation chambers are available for all positive integer costs (1, 2, 3, …).

An isolation chamber can be used multiple times, and each use will

incur the same cost. The robot can also recover a lower number of rods

than a chamber's capacity on a sortie.

Find the minimal cost to recover all the radioactive rods by completing

the given function.

Input

The first parameter integer n specifies the number of rods. The second

parameter pairs is an array of pairs of rods that are fused together. Each

item in the array contains exactly two integers, P and Q separated by a

space (" "), which means that the rod numbered P is fused to the rod

numbered Q. *Note - Each item in the array is a string which needs to be

parsed to P and Q

Output

2

Constraints

2 ≤ N ≤ 100,000

1 ≤ P, Q ≤ N

P ≠ Q

Sample Input

4

2

1 2

1 4

Sample Output

3

Explanation

Rods #1, #2, #4 are connected to each other (2-1-4) so they are in a

single group of 3. The sortie to recover them will cost 2 (with isolation

chamber capacity 2 = 4). Rod #3 is not fused to any other, so it can be

recovered at a cost of 1 (with isolation chamber capacity 1 = 1).| Report Duplicate | Flag | PURGE

Practo SDE1 - 0of 0 votes

AnswersStringChain

- rayasamharish October 04, 2015 in India

You are given a library with n words (w[0], w[1], ..., w[n - 1]). You

choose a word from it, and in each step, remove one letter from this

word only if doing so yields a another word in the library. What is the

longest possible chain of these removal steps?

Constraints:

1 ≤ n ≤ 50000

1 ≤ the length of each string in w ≤ 50

Each string composed of lowercase ascii letters only.

Input Format:

Complete the function "longest_chain" which contains an array of

strings "w" as its argument.

Output Format:

Return a single integer that represents the length of the longest chain of

character removals possible.

Sample Input #00:

6

a

b

ba

bca

bda

bdca

Sample Output #00:

4| Report Duplicate | Flag | PURGE

Practo SDE1 - 0of 0 votes

AnswersTwo numbers A and B are given with same number of digits. A power number of any number is formed by right shift of the given number and it does not contain any leading zeroes and containing same number of digits. Given A and B you have to tell how many such pairs of given number and the power number lie between A and B inclusive.

- ritwik_pandey September 01, 2015 in United States

power numer of 134 are 413 and 341.

111 has no power number.

101 has 110 only as the power number.

note: brute force approach does not pass all test cases. an optimized approach is required.

input

10 40

output

3

/* 12 21, 13 31, 23 32 */| Report Duplicate | Flag | PURGE

Practo Development Support Engineer - 0of 0 votes

AnswersBy tossing a coin we can get either head or tail, i have a function toss() which return head or tail with equal probability.

- rohit January 16, 2015 in India

You have to write a function for dice which will return number from 1-6 with equal probability.

constraints : you can not use random function, you can use only toss function.| Report Duplicate | Flag | PURGE

Practo Software Engineer / Developer Algorithm

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