ISC Practical 2027: Sentence and Date (Vowels, Future Date, Sort by Length) – Algorithm and Java Program

import java.util.Scanner;

/**
 * ISC Practical 2027 - Sample Paper 4, Question 3
 * Counts the vowels (V) in a sentence, adds V days to a date and
 * sorts the words by length, keeping the original order for equal lengths.
 */
public class SentenceDate
{
    String sent;         // sentence ending with . ? or !
    String words[];      // words of the sentence
    int dd, mm, yy;      // the date

    boolean isLeap(int y)
    {
        return (y % 4 == 0 && y % 100 != 0) || y % 400 == 0;
    }

    int daysInMonth(int m, int y)
    {
        int days[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
        return (m == 2 && isLeap(y)) ? 29 : days[m - 1];
    }

    // ends with . ? or ! and the words contain only letters, separated by single spaces
    boolean validSentence(String s)
    {
        sent = s.trim();
        int len = sent.length();
        if (len < 2)
            return false;
        char last = sent.charAt(len - 1);
        if (last != '.' && last != '?' && last != '!')
            return false;
        String body = sent.substring(0, len - 1);
        if (body.startsWith(" ") || body.endsWith(" ") || body.indexOf("  ") >= 0)
            return false;
        for (int i = 0; i < body.length(); i++)
            if (!Character.isLetter(body.charAt(i)) && body.charAt(i) != ' ')
                return false;
        words = body.split(" ");
        return true;
    }

    boolean validDate(String d)
    {
        d = d.trim();
        if (d.length() != 10 || d.charAt(2) != '/' || d.charAt(5) != '/')
            return false;
        for (int i = 0; i < 10; i++)
            if (i != 2 && i != 5 && !Character.isDigit(d.charAt(i)))
                return false;
        dd = Integer.parseInt(d.substring(0, 2));
        mm = Integer.parseInt(d.substring(3, 5));
        yy = Integer.parseInt(d.substring(6));
        return mm >= 1 && mm <= 12 && yy >= 1 && dd >= 1 && dd <= daysInMonth(mm, yy);
    }

    int countVowels()
    {
        int v = 0;
        for (int i = 0; i < sent.length(); i++)
            if ("AEIOUaeiou".indexOf(sent.charAt(i)) >= 0)
                v++;
        return v;
    }

    // moves the date forward by n days, one day at a time
    void addDays(int n)
    {
        for (int k = 1; k <= n; k++)
        {
            dd++;
            if (dd > daysInMonth(mm, yy))
            {
                dd = 1;
                mm++;
                if (mm > 12)
                {
                    mm = 1;
                    yy++;
                }
            }
        }
    }

    // insertion sort on word length: stable, so equal lengths keep their order
    void sortWords()
    {
        for (int i = 1; i < words.length; i++)
        {
            String key = words[i];
            int j = i - 1;
            while (j >= 0 && words[j].length() > key.length())
            {
                words[j + 1] = words[j];
                j--;
            }
            words[j + 1] = key;
        }
    }

    String two(int x)
    {
        return (x < 10 ? "0" : "") + x;
    }

    public static void main(String args[])
    {
        Scanner sc = new Scanner(System.in);
        SentenceDate ob = new SentenceDate();
        System.out.print("Sentence: ");
        String s = sc.nextLine();
        System.out.print("Date: ");
        String d = sc.nextLine();
        if (!ob.validSentence(s))
        {
            System.out.println("INVALID SENTENCE");
            return;
        }
        if (!ob.validDate(d))
        {
            System.out.println("INVALID DATE");
            return;
        }
        int v = ob.countVowels();
        ob.addDays(v);
        System.out.println("NUMBER OF VOWELS = " + v);
        System.out.println("FUTURE DATE (AFTER " + v + " DAYS): "
                + ob.two(ob.dd) + "/" + ob.two(ob.mm) + "/" + ob.yy);
        ob.sortWords();
        System.out.println("SORTED WORDS BY LENGTH:");
        String out = "";
        for (int i = 0; i < ob.words.length; i++)
            out += ob.words[i] + "  ";
        System.out.println("    " + out.trim());
    }
}

Name           Type       Purpose
-------------  ---------  -------
sent           String     sentence entered by the user
words[]        String[]   words of the sentence
dd, mm, yy     int        the date, moved forward by V days
v              int        number of vowels
key            String     word being inserted during the sort
i, j           int        loop indexes for the insertion sort

INPUT:
Sentence: The sun is bright today.
Date: 20/01/2024

OUTPUT:
NUMBER OF VOWELS = 6
FUTURE DATE (AFTER 6 DAYS): 26/01/2024
SORTED WORDS BY LENGTH:
    is  The  sun  today  bright

INPUT:
Sentence: AI is amazing and useful?
Date: 28/02/2024

OUTPUT:
NUMBER OF VOWELS = 10
FUTURE DATE (AFTER 10 DAYS): 09/03/2024
SORTED WORDS BY LENGTH:
    AI  is  and  useful  amazing

INPUT:
Sentence: Good Morning everyone.
Date: 31/04/2024

OUTPUT:
INVALID DATE

INPUT:
Sentence: Happy new year everyone!
Date: 28/12/2025

OUTPUT:
NUMBER OF VOWELS = 8
FUTURE DATE (AFTER 8 DAYS): 05/01/2026
SORTED WORDS BY LENGTH:
    new  year  Happy  everyone

INPUT:
Sentence: Practice every day
Date: 10/10/2026

OUTPUT:
INVALID SENTENCE