Question

Data Structure

Hi, could you please help with the following question in Java

a. Suppose we have some List of Strings called list and a String prefix. Write a method that removes all the Strings from list that begin with prefix.

public static <E> void removePrefixStrings(List<String> list, String prefix) {

write your method here

}

b. What is the time complexity of the method you wrote?

Answer 1

Hi,

here i am providing sample code for above problem along with Sample output.

Sample Code:-

--------------------

package simplejavaapplication;

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

/**
* main method to starts the execution of a program
*
* @author DELL
*/
public class StringApp {

public static void main(String[] args) {
// A prefix of a string is a substring of that occurs at the beginning of String.
//Decalring list collection framework as of type String
List<String> strings = new LinkedList<>();
strings.add("Welcome to Chegg India");
strings.add("HomeworkLib India");
strings.add("HomeworkLib India Platform Welcomes You");
//let us take prefix as Chegg.
String prefix = "HomeworkLib";
removePrefixStrings(strings, prefix);
}

/**
* Method to remove all strings from the list that contains the prefix
* "Chegg"
*
* @param strings
* @param prefix
*/
public static void removePrefixStrings(List<String> strings, String prefix) {
System.out.println("Original String Tokens " + strings.toString());
strings.forEach(StringToken -> {
System.out.println("Token " + Arrays.toString(StringToken.split(prefix)));
});
}

}

Sample output:-

--------------------

run:
Original String Tokens [Welcome to Chegg India, HomeworkLib India, HomeworkLib India Platform Welcomes You]
Token [Welcome to Chegg India]
Token [, India]
Token [, India Platform Welcomes You]
BUILD SUCCESSFUL (total time: 0 seconds)

Time Complexity for the above Solution is:

It takes O(1) to remove all prefixes from that string that matches with given list of Strings.

Since while comparing prefix with list of all strings initially will look at the first index of strings

So it wont compare with all tokens/words of a given list of String.

please let me know if want any clarification.

QSearch (Ctrl+1) Navigator 4 11 SimpleJavaApplication - NetBeans IDE 8.0.2 File Edit View Navigate Source Refactor Run Debug Profile Team Tools Window Help 20 0 <default config> v R - Projects x Files Services StringApp.java x #- ICONacademy Source History ...079 PBBO N - - SimpleJavaApplication -@ Source Packages + 3 com.in.HomeworkLibprograms public class StringApp { simplejavaapplication SimpleJavaApplication.java public static void main(String[] args) { LG StringApp.java V/ A prefix of a string is a substring of that occurs at the beginning of String. + Libraries //Decalring list collection framework as of type String List<String> strings = new LinkedList<>(); strings.add("Welcome to Chegg India"); strings.add("HomeworkLib India"); strings.add("HomeworkLib India Platform welcomes You"); //let us take prefix as Chegg. String prefix = "HomeworkLib"; remove PrefixStrings (strings, prefix); * Method to remove all strings from the list that contains the prefix * "Chegg * @param strings * @param prefix public static void removePrefixStrings (List<String> strings, String prefix) { System.out.println("Original String Tokens " + strings.toString()); strings.forEach(StringToken -> { System.out.println("Token " + Arrays.toString (StringToken.split (prefix))); }); simplejavaapplication.StringApp >