Leet Code Roman to Integer

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

Symbol       Value
I                   1
V                  5
X                 10
L                  50
C                 100
D                 500
M               1000

  For example, 2 is written as II in Roman numeral, just two ones added together. 12 is written as XII,       which is simply X + II. The number 27 is written as XXVII, which is XX + V + II.

 Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is   not IIII. Instead, the number four is written as IV. Because the one is before the five we subtract it making   four. The same principle applies to the number nine, which is written as IX. There are six instances where   subtraction is used:

• I can be placed before V (5) and X (10) to make 4 and 9. 
• X can be placed before L (50) and C (100) to make 40 and 90. 
• C can be placed before D (500) and M (1000) to make 400 and 900.

 Given a roman numeral, convert it to an integer.

 

 Example 1:

Input: s = "III"
Output: 3
Explanation: III = 3.

 Example 2:

Input: s = "LVIII"
Output: 58
Explanation: L = 50, V= 5, III = 3.

 Example 3:

Input: s = "MCMXCIV"
Output: 1994
Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.

 

 Constraints:

• 1 <= s.length <= 15
• s contains only the characters ('I', 'V', 'X', 'L', 'C', 'D', 'M').
• It is guaranteed that s is a valid roman numeral in the range [1, 3999].

 Explanation:

The logic of the program is explained below with the example of MCMXCIV.

Take the value of each of the letters in the sequence:

1000 = M, 100 = C, 1000 = M, 10 = X, 100 = C, 1 = I, 5 = V

Keed adding the values in a variable. But for the second position onwards we

have check the difference of the value of the current position and the previous

position. If the difference is 4 or 9 or 40 or 90 or 400 or 900 then by the exception

rule we have to adjust the value.

For the example above, as 100-1000 = -900 ( i = 1 and i = 0) which is not under

exception rule we add 1000+100 = 1100

But for the next letter ('M') the value is 1000 ( i = 2 ) and 1000 - 100 = 900

( under exception rule), so instead of adding 1000 to 1100 we have to have add 900

to the value of the first letter ( since CM is forming a single value). For this

we need to subtract the value of the current letter (M = 1000) and the previous

letter ( C = 100 ) from the sum of 1000+100+1000 = 2100 and add 900.

Which gives 2100-1000 - 100 + 900 = 1900.

PYTHON CODE

class Solution(object):

    def romanToInt(self, s):

        temp = 0

        for i in range(len(s)):

            self.output += self.value[self.position(s[i])]

            #print ("BEFORE ADJUSTMENT",self.output)

            if i > 0:

                temp = (self.value[self.position(s[i])] -

                        self.value[self.position(s[i - 1])])

            if temp == 4 or temp == 9 or temp == 40 or temp == 90 or temp == 400 or temp == 900:

                self.output = self.output - self.value[self.position(

                    s[i - 1])] - self.value[self.position(s[i])] + temp

            #print ("AFTER ADJUSTMENT",self.output)

        return self.output

    def position(self, symb):

        counter = 0

        while symb != self.symbol[counter]:

            counter += 1

        return (counter)

    symbol = ['I', 'V', 'X', 'L', 'C', 'D', 'M']

    value = [1, 5, 10, 50, 100, 500, 1000]

    output = 0

obj = Solution()

s = str(input("Enter a valid roman numeral in range(1,3999):"))

print(obj.romanToInt(s))

ISC COMPUTER SCIENCE PRACTICAL SPECIMEN PAPER 2021 : QUESTION 2 STRING

ISC COMPUTER SCIENCE PRACTICAL SPECIMEN PAPER 2021

Try out with different inputs

ENTER THE SENTENCE:

 import java.io.*;

public class ISC2021SpecimenQuestion2{

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

               String Sentence;

               boolean lowerflag;

               boolean spaceflag;

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

               do {

                 

               System.out.println("Enter the sentence:");

               Sentence=br.readLine();

               if( Sentence.charAt(Sentence.length()-1)!= '.' 

                     && Sentence.charAt(Sentence.length()-1)!= '?' 

                     && Sentence.charAt(Sentence.length()-1)!= '!') //end of if

                  System.out.println("INVALID INPUT:,TRY AGAIN");

                  lowerflag = true;

                  spaceflag = true;

                  // checking for lowercase

                  for(int i = 0; i<Sentence.length();i++)

                     if(!Character.isLowerCase(Sentence.charAt(i)) && Character.isLetter(Sentence.charAt(i))) {

                         lowerflag = false;

                         System.out.println("Must be in lower case,TRY AGAIN");

                         break;

                         }

                  //checking for more than one space

                  for(int i = 0; i<Sentence.length()-1;i++)

                         if(Sentence.charAt(i) ==' ')

                            if(Sentence.charAt(i+1) == ' ') {

                                   spaceflag = false;

                                   System.out.println("Words must be seperated by a single space");

                                   break;

                            }

               } while((Sentence.charAt(Sentence.length()-1)!= '.' 

                     && Sentence.charAt(Sentence.length()-1)!= '?' 

                     && Sentence.charAt(Sentence.length()-1)!= '!')

                     || lowerflag==false || !spaceflag); //end of do-while

               SenetenceSort obj = new SenetenceSort(Sentence);

               System.out.println("OUTPUT:");

               char c = Character.toUpperCase(Sentence.charAt(0));

               Sentence = String.valueOf(c) + Sentence.substring(1,Sentence.length() ); 

               System.out.println(Sentence);

               obj.wordExtractor();

               obj.sortWords();

               obj.display();

               br.close();

       }

}

class SenetenceSort{

       public void display() {

              char c = Character.toUpperCase(word_Storage[0].charAt(0));

              word_Storage[0] = String.valueOf(c) + word_Storage[0].substring(1,word_Storage[0].length() ); 

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

                     if(i==word_counter-1)

                           System.out.print(word_Storage[i]+msg.charAt(msg.length()-1));

                     else

                           System.out.print(word_Storage[i]+" ");

                     }

       }

       public void sortWords() {

              String temp;

              int i,j;

              for(i = 0;i<word_counter-1; i++)     

                       for (j = 0; j < word_counter-i-1; j++)

                       // sorting length wise - only if lengths are different ( no equal sign is placed)

                         if (word_Storage[j].length() > word_Storage[j+1].length()) { 

                              temp=word_Storage[j+1];

                            word_Storage[j+1]=word_Storage[j];

                            word_Storage[j]=temp;

                            }

        }      

       public void wordExtractor() {

              int i;

              //counting the number of words

              for(i=0;i<msg.length();i++)

                if(msg.charAt(i)== ' ')

                       word_counter++;

              word_counter +=1; // In any sentence, number of words is 1 greater than the number of spaces

              word_Storage = new String[word_counter];

              int k = 0;

              //extracting words

              for(i=0;i<msg.length();i++) {

                word_Storage[k]="";

                while(msg.charAt(i) != ' ' &&  i < msg.length()-1) { 

                             word_Storage[k] +=msg.charAt(i);

                             i++;

                            }

                k++;

                       } // end of i-loop

                     }

     

      

       SenetenceSort(String Sentence){

              this.msg=Sentence;

              this.word_counter=0;

       }

       private String msg;

       private int word_counter;

       private String[] word_Storage;

}

In most of the problems based on Strings in ISC Computer Science Practical it is common to test the validity of the sentence. In most of the cases the statement is terminated by either '.', '?' or '!' and are separated by a single blank and have only upper case characters or only lower case characters.

                            In most of my programs I have checked only for the terminating characters and the case for the characters. But in this program I have tested that the word must be separated by only one blank as well as the for the terminating characters. This will serve the blue print of all your programs involving strings. Also remember extracting words from a string forms a vital tradition of ISC practical programs and I have used this logic in almost all my programs under the method name "wordExtractor()". You should be familiar with all the above mention methods very well! Any comment is always welcome :)

ISC COMPUTER SCIENCE PRACTICAL SPECIMEN QUESTION PAPER 2021 QUESTION 1 : DATE AFTER

 

As per the given criteria we will first check the inputs before passing the variables to the constructor.

do {

           System.out.println("Enter the day number:");

           day = in.nextInt();

           if(day < 1 || day > 366)

                System.out.println("INVALID DAY:");

           System.out.println("Enter the year:");

           yr = in.nextInt();

           if(Integer.toString(yr).length() !=4)

                System.out.println("INVALID YEAR:");

           System.out.println("Enter the value of N:");

           N = in.nextInt();

           if(N < 1 || N > 100)

                System.out.println("INVALID DATA:");

       }while(day < 1 || day > 366 || Integer.toString(yr).length() !=4 ||  N < 1 || N > 100 );

       DaysCalculation obj = new DaysCalculation(day, yr, N);

Now the main task of the program is to calculate the date in the format: Day: Month: Year

for given day ( 1<= day <= 366).

To this I have use the function obj.currentDay(); the logic is as follows:

I am assuming that the entered year is a non-leap year, the same goes for the leap-year.

Between to check a year is leap or not I have employed the method

private boolean checkLeap(int year)

which is easy to decode.

Now coming back to the main theme, suppose a user enters 70, 2017 and 50 as the input.

First we need to calculate the date of 70th day of the year 2017 and then the date after 50

days from the current date.

Since 2017 is a non-leap year, the months will have the following days:

private int[] mdays={31,28,31,30,31,30,31,31,30,31,30,31};

First we have to calculate the month in which the 70th day fall, for this add up the

elements of the array mdays starting from 0th position until the sum exceeds the day number 70.

So in our example, 31+28+31 = 90 > 70

So the 70th day of the year falls in the 3rd month.

This has been implemented by the following snippet of code:

if(checkLeap(year)) {

        sum += ldays[counter];

        while( sum  < dayNumber) {  

            monthCounter++;

            sum +=ldays[counter+1];

            counter++;

        }

    }

    else{

        sum += mdays[counter];

        while( sum  < dayNumber) {  

            monthCounter++;

            sum +=mdays[counter+1];

            counter++;  

        }

    }

Once we get the month, the next task is to calculate the day of the current month.

This is too easy, just subtract the day number ( 70th in our case ) from the

sum of the days of all the previous months.

In our case this will give 70-(31+28) = 11th day of the 3rd month.

    sum = 0;

    if(checkLeap(year))

        for(int i = 0; i < monthCounter; i++)

            sum +=ldays[i];

    else

        for(int i = 0; i < monthCounter; i++)

            sum +=mdays[i];

    int fdayNumber;

    fdayNumber = dayNumber; 

    fdayNumber -= sum;

Note fdayNumber is just a temporary variable to store the value of dayNumber.

After this we just need to print the day and month and year;

Now the next task is to find the day after 50 days, so the logic is as follows:

add the dayNumber and 50 ( 70 + 50 = 120 ) in our case. Check if this value crosses

365 ( for non-leap year), if so, subtract 365 from it and increment the year.

So now we have a day number and year so just call the function discussed above!

public void dateAfter() {

        dayNumber +=dayAfter;

        if(checkLeap(year)) {

            if(dayNumber > 366 ) {

                dayNumber -= 366;

                year++;

                }

            currentDay();   

            }

        else {

            if(dayNumber > 365) {

                dayNumber -= 365;

                year++;

                }

            currentDay();

        }   

    

    }  

JAVA CODE

import java.util.*;

public class ISC2021SpecimenQuestion1 {

    public static void main(String[] args) {

       int day;

       int yr;

       int N;

       Scanner in = new Scanner(System.in);

       do {

           System.out.println("Enter the day number:");

           day = in.nextInt();

           if(day < 1 || day > 366)

                System.out.println("INVALID DAY:");

           System.out.println("Enter the year:");

           yr = in.nextInt();

           if(Integer.toString(yr).length() !=4)

                System.out.println("INVALID YEAR:");

           System.out.println("Enter the value of N:");

           N = in.nextInt();

           if(N < 1 || N > 100)

                System.out.println("INVALID DATA:");

       }while(day < 1 || day > 366 || Integer.toString(yr).length() !=4 ||  N < 1 || N > 100 );

       DaysCalculation obj = new DaysCalculation(day, yr, N);

       System.out.println("OUTPUT:");

       obj.currentDay();

       System.out.println("DATE AFTER "+N+" DAYS");

       obj.dateAfter();

       in.close();

    }  

}

class DaysCalculation {

    public void currentDay() {

    int counter = 0;

    int monthCounter = 0;

    int sum =0;

    if(checkLeap(year)) {

        sum += ldays[counter];

        while( sum  < dayNumber) {  

            monthCounter++;

            sum +=ldays[counter+1];

            counter++;

        }

    }

    else{

        sum += mdays[counter];

        while( sum  < dayNumber) {  

            monthCounter++;

            sum +=mdays[counter+1];

            counter++;  

        }

    }

    sum = 0;

    if(checkLeap(year))

        for(int i = 0; i < monthCounter; i++)

            sum +=ldays[i];

    else

        for(int i = 0; i < monthCounter; i++)

            sum +=mdays[i];

    int fdayNumber;

    fdayNumber = dayNumber; 

    fdayNumber -= sum;

    String s = fdayNumber%10 == 1 ? "st" : fdayNumber%10 == 2 ? "nd" : fdayNumber%10 == 3 ? "rd" : "th";

    if(fdayNumber >= 11 && fdayNumber <= 19)

        s= "th";

    System.out.println(fdayNumber+s+" "+months[monthCounter]+" "+year); 

    }

    public void dateAfter() {

        dayNumber +=dayAfter;

        if(checkLeap(year)) {

            if(dayNumber > 366 ) {

                dayNumber -= 366;

                year++;

                }

            currentDay();   

            }

        else {

            if(dayNumber > 365) {

                dayNumber -= 365;

                year++;

                }

            currentDay();

        }   

    

    }  

    private boolean checkLeap(int year) {

        if(year%400==0)

           leap=true;

        else if (year%100==0)

           leap=false;

        else if (year%4==0)

           leap=true;

        else

           leap=false;

        return leap;

    }   

    DaysCalculation(int day, int yr, int N) {

        this.dayNumber = day;

        this.year = yr;

        this.dayAfter =N;

    }

    private boolean leap;  

    private int dayNumber;

    private int year;

    private int dayAfter;

    private String[] months = {"January","Feburary","March","April","May","June","July","August","Sepetember","October","November","December"};

    private int[] mdays={31,28,31,30,31,30,31,31,30,31,30,31};

    private int[] ldays={31,29,31,30,31,30,31,31,30,31,30,31};  

}