**[Question/Problem Statement is the Property of HackerRank]**

**Algorithms/Data Structures -****[Problem Solving]**

**Example**n = 23

"customers = {"Bigcorp", "Bigcorp", "Acme", "Bigcorp", "Zork", "Zork", "Abe", "Bigcorp", "Acme", "Bigcorp", "Bigcorp" , "Zork", "Bigcorp", "Zork", "Zork", "Bigcorp", "Acme", "Bigcorp", "Acme", "Bigcorp", "Acme",""Littlecorp" , "Nadircorp "}."

"Bigcorp had 10 Trades out of 23,which is 43.48% of the Total Trades."

"Both Acme and Zork had 5 trades,which is 21.74% of the Total Trades."

"The Littlecorp, Nadircorp and Abe had 1 Trade Each, which is 4.35%..."

"So the Answer is [""Acme"", "" Bigcorp ,""Zork""] (In Alphabetical Order) Because only These Three Companies Placed atleast 5% of the Trades.

Function Description

Complete the Function ** mostActive** in the Editor Below.

*has the following parameter:*

mostActivemostActive

String customers[n] : An Array Customer Names

(Actual Question Says String Array, But Signature is List of Strings)

Returns String[] : An Alphabetically Ascending Array

Constraints

• 1 < n < 10^5

• 1 < Length of customers[] < 20

• The First Character of customers[i] is a Capital English letter.

• All Characters of customers[i] except for the First One are Lowercase.

• Guaranteed that At least One Customer makes atleast 5% of Trades.

Input Format

"The First Line contains an integer, n, The Number of Elements in customers."

"Each Line iof the n Subsequent Lines (where 0 s i< n) contains a string, customers[i]." *Sample Case 0 Input For Custom Testing*

20

Omega Alpha Omega Alpha Omega Alpha Omega Alpha Omega Alpha Omega Alpha Omega Alpha Omega Alpha Omega Alpha Omega Beta *Function **mostActive*** **

customers[] size n = 20

customers[] = [As Provided Above]

Sample Output

Alpha

Beta

Omega

Explanation

"Alpha made 10 Trades out of 20 (50% of the Total), Omega made 9 Trades (45% of the Total). and Beta made 1 Trade (5% of the Total).All of them have met the 5% Threshold, so all the Strings are Returned in an Alphabetically Ordered Array."

**[Explanation of the Solution]**

This is Good Practice for the Brain for Problem Solving - Involves Simple Arithmetic and Mathematical Application. Ideally, A Programmer would want to Optimize the Solution in Space and Time (Which I Did Not :-)

**[Source Code, Sumith Puri (c) 2021 - Free to Use & Distribute]**

`import static java.util.stream.Collectors.joining;`

import static java.util.stream.Collectors.toList;

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.ArrayList;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.TreeMap;

import java.util.stream.IntStream;

/*

* HackerRank Problem Solving - Ain't a Horse that Can't be Rode

* Sumith Kumar Puri (c) 2021 - ~ Bengaluru, Karnataka, India ~

*

*/

class ActiveTradersLogic {

public static List<String> mostActive(List<String> customers) {

// How About Arrays or Custom LinkedList for a 'Very Fast' Traversal?

Map<String, Integer> customerMap = new TreeMap<String, Integer>();

List<String> solutionStr = new ArrayList<String>();

int customerMapSize = customers.size();

for (int i = 0; i < customerMapSize; i++) {

String customerKey = customers.get(i);

if (customerMap.containsKey(customerKey)) {

Integer customerCount = customerMap.get(customerKey);

customerMap.put(customerKey, ++customerCount);

} else {

customerMap.put(customerKey, 1);

}

}

Set<String> customerMapKeys = customerMap.keySet();

for (String customerKey : customerMapKeys) {

Integer customerCount = customerMap.get(customerKey);

double currentCustomerPercent = (double) (customerCount) / (double) customerMapSize;

if (currentCustomerPercent * 100 >= 5.0) {

solutionStr.add(customerKey);

}

}

return solutionStr;

}

}

public class ActiveTraders {

public static final String OUTPUT_PATH = "PROVIDE_ABSOLUTE_INPUT_FILE_NAME";

public static void main(String[] args) throws IOException {

BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv(OUTPUT_PATH)));

int customersCount = Integer.parseInt(bufferedReader.readLine().trim());

List<String> customers = IntStream.range(0, customersCount).mapToObj(i -> {

try {

return bufferedReader.readLine();

} catch (IOException ex) {

throw new RuntimeException(ex);

}

}).collect(toList());

List<String> result = ActiveTradersLogic.mostActive(customers);

bufferedWriter.write(result.stream().collect(joining("\n")) + "\n");

bufferedReader.close();

bufferedWriter.close();

}

}

**!**

*Happy Problem Solving using Java*
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