SKP's Algorithms and Data Structures #5: Java Problem: Changes in Usernames
This Article Series Focuses on Algorithms, Data Structures, or Applying them to Problem Solving. In this Article, We Discuss the Solution to [Usernames Changes] Problem from Hacker Rank.
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Join For Free[Question/Problem Statement is the Adapted from HackerRank]
Algorithms/Data Structures — [Problem Solving]
There is a Specific Need for Changes in a List of Usernames. In a given List of Usernames — For Each Username — If the Username can be Modified and Moved Ahead in a Dictionary. The Allowed Modification is that Alphabets can change Positions in the Given Username.
Example
usernames[] = {"Aba", "Cat"}
"Aba" can be Changed to only "Baa" — Hence, It can Never Find a Place Ahead in the Dictionary. Hence, Output will be "NO". "Cat" can be Changed to "Act", "Atc", "Tca", "Tac", "Cta" and Definitely "Act" will Find a Place Before "Cat" in the Dictionary. Hence, Output will be "YES".
[Function Description]
Complete the function possibleChanges in the Editor Below.
possibleChanges has the Following Parameters:
String usernames[n]: An Array of User Names
String usernames[n]: An Array of User Names
Returns String[n]: An Array with "YES" or "NO" Based on Feasibility
(Actual Question Says String Array, But Signature is List of Strings)
(Actual Question Says String Array, But Signature is List of Strings)
Constraints
• [No Special Constraints Exist, But Cannot Recall Exactly]
• [No Special Constraints Exist, But Cannot Recall Exactly]
Input Format
"The First Line Contains an Integer, n, the Number of Elements in Usernames.",
"Each Line of the n Subsequent Lines (where 0 < i < n) contains a String usernames[i]."
[Sample Case 0 — Sample Input For Custom Testing]
5
Aba
Cat
Boby
Buba
Bapg
Sungi
Lapg
Acba
Sample Output (Each Should Be on a Separate Line)
NO YES NO YES YES YES YES YES
This is again a Good Question from Hacker Rank to Test Your Logic / Problem Solving Abilities. The Core Point to Handle is that For Each Combination of 2 Alphabets that Exists in the Username String > We Need to Check if the Latter Occurring Character (ASCII) is Less than the Former Occurring Character (ASCII). For Example in the String "Bapg" — For a Selection of "Ba" from "Bapg" — We have "a" Occurring Before "B" in the English Alphabet. We can Have Two Loops (One Nested) to Decide for a Combination of Each Two Alphabets. The Time Complexity of this Solution is O(n^2).
[Source Code, Sumith Puri (c) 2021 — Free to Use and 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.stream.IntStream;
/*
* HackerRank Problem Solving - Speak Ur Mind, But Ride a Fast Horse.
* ~ Sumith Kumar Puri (c) 2021 ~ -- ~ Bengaluru, Karnataka, India ~
*
*/
class UsernamesChangesLogic {
public static List<String> possibleChanges(List<String> usernames) {
List<String> solutionStr = new ArrayList<String>();
boolean bobbysFlag = false;
for (String username : usernames) {
bobbysFlag = false;
String currName = username.toLowerCase();
for (int i = 0; i < currName.length(); i++) {
int a = currName.charAt(i);
for (int j = i + 1; j < currName.length(); j++) {
int b = currName.charAt(j);
if (b < a) {
bobbysFlag = true;
break;
}
}
if (bobbysFlag) {
solutionStr.add("YES");
break;
}
}
if (!bobbysFlag)
solutionStr.add("NO");
}
return solutionStr;
}
}
public class UsernamesChanges {
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 usernamesCount = Integer.parseInt(bufferedReader.readLine().trim());
List<String> usernames = IntStream.range(0, usernamesCount).mapToObj(i -> {
try {
return bufferedReader.readLine();
} catch (IOException ex) {
throw new RuntimeException(ex);
}
}).collect(toList());
List<String> result = UsernamesChangesLogic.possibleChanges(usernames);
bufferedWriter.write(result.stream().collect(joining("\n")) + "\n");
bufferedReader.close();
bufferedWriter.close();
}
}
Happy Problem Solving using Java!
Java (programming language)
Data (computing)
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