ISC practical papers › ISC 2019 › Question 3

Convert words to Palindromes

ISC 2019 Computer Science Practical, Question 3 · Strings

The question

Write a program to accept a sentence which may be terminated by either ‘.’ , ‘?’ or ‘!’ only. The words are to be separated by a single blank space and are in UPPER CASE.

Perform the following tasks: (a) Check for the validity of the accepted sentence. (b) Convert the non-palindrome words of the sentence into palindrome words by concatenating the word by its reverse (excluding the last character).

Example: The reverse of the word HELP would be LEH (omitting the last alphabet) and by concatenating both, the new palindrome word is HELPLEH. Thus, the word HELP becomes HELPLEH.

Note: The words which end with repeated alphabets, for example ABB would become ABBA and not ABBBA and XAZZZ becomes XAZZZAX. [Palindrome word: Spells same from either side. Example: DAD, MADAM etc.] (c) Display the original sentence along with the converted sentence.

Test your program for the following data and some random data:
Example 1
INPUT:
THE BIRD IS FLYING.
OUTPUT:
THE BIRD IS FLYING.
THEHT BIRDRIB ISI FLYINGNIYLF

Example 2
INPUT:
IS THE WATER LEVEL RISING?
OUTPUT:
IS THE WATER LEVEL RISING?
ISI THEHT WATERETAW LEVEL RISINGNISIR

Example 3
INPUT:
THIS MOBILE APP LOOKS FINE.
OUTPUT:
THIS MOBILE APP LOOKS FINE.
THISIHT MOBILELIBOM APPA LOOKSKOOL FINENIF

Example 4
INPUT:
YOU MUST BE CRAZY#
OUTPUT:
INVALID INPUT

Question: ISC 2019 Computer Science Paper 2 (Practical), Question 3, set by the Council for the Indian School Certificate Examinations (CISCE). Solution and video: Vinay Singh.

Java solution

ISC2019Q3.java Download GitHub

import java.util.*;

public class ISC2019Q3 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("INPUT");
        String sentence=in.nextLine();
        MyString str = new MyString(sentence);
        System.out.println("OUPUT");
        if(str.isValid()){
            System.out.println(sentence);
            str.convertToPalindrome();
            System.out.println(str);
        }else{
            System.out.println("INVALID INPUT");
        }
        in.close();
    }
}
class MyString{
    private String sentence, words[];
    public MyString(String sentence){
        this.sentence=sentence;
    }
    public boolean isValid(){
        return ".?!".indexOf(sentence.charAt(sentence.length()-1))>=0;
    }
    public void convertToPalindrome(){
        String reverse="";
        int delta;
        sentence=sentence.substring(0, sentence.length()-1);
        words=sentence.split(" ");
        for( int i=0; i<words.length;i++){
            if(!isPalindrome(words[i])){
                reverse="";
                if(words[i].length()>2 && words[i].charAt(words[i].length()-1)==words[i].charAt(words[i].length()-2)){
                    delta=1;
                }else{
                    delta=0;
                }
                for(int position=0; position<words[i].length()-1-delta;position++){
                    reverse=words[i].charAt(position)+reverse;
                }
                words[i]=words[i]+reverse;
            }
        }
    }
    public static boolean isPalindrome(String source){
        int half=source.length()/2;
        for( int position=0; position<=half;position++){
            if(source.charAt(position)!=source.charAt(source.length()-1-position)) 
            return false;
        }
        return true;
    }
    public String toString(){
        String output="";
        for(String word:words){
            output+=word+" ";
        }
        return output;
    }
}

Convert words to Palindromes

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