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Chapter 1 - Unit 9

Nested Loop

Class 10 - APC Understanding Computer Applications with BlueJ


Write whether the following statements are True/False

Question 1

Nested loop contains a single loop.
False

Question 2

When break statement is applied, it terminates the loop.
True

Question 3

The outer loop follows next iteration when iterations of inner loop is over.
True

Question 4

Nested loop means the using of two or more loops in a program.
False

Question 5

Labelled break statement allows the next iteration of the loop from any place of looping structure.
False

Question 6

In a nested loop, break and continue can be used simultaneously.
False

Fill in the blanks

Question 1

Labelled break is used to terminate an outer loop.

Question 2

A loop within another loop is called nested loop.

Question 3

Termination of inner loop takes place before outer loop.

Question 4

continue statement will repeat a loop for the next iteration after ignoring some statements of the loop.

Question 5

break statement terminates a switch-case statement as well as a loop.

Answer the following questions

Question 1

What is a nested loop?

When a loop is contained inside another loop it is termed as nested loops

Question 2

Write down the syntax of a nested for loop.

Below is the syntax of nested loop:

  
for (<initial value>; <test condition>; <update value>) {
    for (<initial value>; <test condition>; <update value>) {
        executable statement(s)
    }
}

Question 3

What action will you take to terminate an outer loop from the block of an inner loop?

An outer loop can be terminated from the block of an inner loop by using Labelled break statement as shown in the below example:

outer: for (int i = 1; i <= 5; i++) {
      for (int j = 1; j <= 10; j++) {
            System.out.println(j);
            if (i == 3)
                  break outer;
      }
}
System.out.println("Outside outer loop");

Question 4

Give two differences between 'Break' and 'Continue'.

breakcontinue
It is used to unconditionally jump out of the loopIt is used to unconditionally jump to the next iteration of the loop, skipping the remaining statements of the current iteration.
It is used in switch-case and loopsIt is only used in loops.

Question 5

What is significance of 'break outer' and 'continue outer' in a nested loop?

'break outer' will terminate the loop that is labelled as outer in a nested loop and transfer the program control to the statement just after the loop labelled as outer.
'continue outer' will skip the remaining statements of the nested loop and start the next iteration of the loop that is labelled as outer.

Question 6

Write down the constructs (syntax) of:

(a) Nested do-while loop

do {
      //statements of outer do-while loop
      ..
      ..
      do {
            //statements of inner do-while loop
      } while (<condition>);
      ..
      ..
} while (<condition>);

(b) Nested while loop

while (<condition>) {
      //statements of outer while loop
      ..
      ..
      while (<condition>) {
            //statements of inner while loop
      }
      ..
      ..
}

Solutions to Unsolved Java Programs

Question 1

Write programs to find the sum of the following series:

(a) S = 1 + (3/2!) + (5/3!) + (7/4!) + ....... to n

import java.util.Scanner;

public class KboatSeries
{
    public void computeSum() {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter n: ");
        int n = in.nextInt();
        double sum = 0.0;
        for (int i = 1, j = 1; i <= n; i++, j = j + 2) {
            double f = 1;
            for (int k = 1; k <= i; k++) {
                f *= k;
            }
            sum += j / f;
        }
        System.out.println("Sum=" + sum);
    }
}
Output
BlueJ output of KboatSeries.java

(b) S = a + (a/2!) + (a/3!) + (a/4!) + ....... + (a/n!)

import java.util.Scanner;

public class KboatSeries
{
    public void computeSum() {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a: ");
        int a = in.nextInt();
        System.out.print("Enter n: ");
        int n = in.nextInt();
        double sum = 0;
        
        for (int i = 1; i <= n; i++) {
            double f = 1;
            for (int j = 1; j <= i; j++) {
                f *= j;
            }
            sum += a / f;
        }
        System.out.println("Sum=" + sum);
        
    }
}
Output
BlueJ output of KboatSeries.java

(c) S = a - (a/2!) + (a/3!) - (a/4!) + ....... to n

import java.util.Scanner;

public class KboatSeries
{
    public void computeSum() {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a: ");
        int a = in.nextInt();
        System.out.print("Enter n: ");
        int n = in.nextInt();
        double sum = 0;
        
        for (int i = 1; i <= n; i++) {
            double f = 1;
            for (int j = 1; j <= i; j++) {
                f *= j;
            }
            if (i % 2 == 0)
                sum -= a / f;
            else
                sum += a / f;
        }
        System.out.println("Sum=" + sum);
        
    }
}
Output
BlueJ output of KboatSeries.java

(d) S = (a/2!) - (a/3!) + (a/4!) - (a/5!) + ....... + (a/10!)

import java.util.Scanner;

public class KboatSeries
{
    public void computeSum() {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a: ");
        int a = in.nextInt();
        double sum = 0;
        
        for (int i = 2; i <= 10; i++) {
            double f = 1;
            for (int j = 1; j <= i; j++) {
                f *= j;
            }
            if (i % 2 == 0)
                sum += a / f;
            else
                sum -= a / f;
        }
        System.out.println("Sum=" + sum);
        
    }
}
Output
BlueJ output of KboatSeries.java

(e) S = (2/a) + (3/a2) + (5/a3) + (7/a4) + ....... to n

import java.util.Scanner;

public class KboatSeries
{
    public void computeSum() {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a: ");
        int a = in.nextInt();
        System.out.print("Enter n: ");
        int n = in.nextInt();
        double sum = 0;
        int lastPrime = 1;

        for (int i = 1; i <= n; i++) {
            for (int j = lastPrime + 1; j <= Integer.MAX_VALUE; j++) {
                boolean isPrime = true;
                for (int k = 2; k <= j / 2; k++) {
                    if (j % k == 0) {
                        isPrime = false;
                        break;
                    }
                }
                
                if (isPrime) {
                    sum += j / Math.pow(a, i);
                    lastPrime = j;
                    break;
                }
            }

        }
        System.out.println("Sum=" + sum);
    }
}
Output
BlueJ output of KboatSeries.java

Question 2

Write a program to input two numbers and check whether they are twin prime numbers or not.
Hint: Twin prime numbers are the prime numbers whose difference is 2.
For example: (5,7), (11,13), ....... and so on.

import java.util.Scanner;

public class KboatTwinPrime
{
    public void twinPrimeCheck() {

        Scanner in = new Scanner(System.in);

        System.out.print("Enter first number: ");
        int a = in.nextInt();

        System.out.print("Enter second number: ");
        int b = in.nextInt();

        boolean isAPrime = true;

        for (int i = 2; i <= a / 2; i++) {

            if (a % i == 0) {
                isAPrime = false;
                break;
            }

        }

        if (isAPrime && Math.abs(a - b) == 2) {
            
            boolean isBPrime = true;
            
            for (int i = 2; i <= b / 2; i++) {

                if (b % i == 0) {
                    isBPrime = false;
                    break;
                }
                
            }
            
            if (isBPrime)
                System.out.println(a + " and " + b + " are twin prime");
            else
                System.out.println(a + " and " + b + " are not twin prime");
        }
        else
            System.out.println(a + " and " + b + " are not twin prime");
    }
}
Output
BlueJ output of KboatTwinPrime.java

Question 3

Write a program to display all the numbers between 100 and 200 which don't contain zeros at any position.
For example: 111, 112, 113, ....... , 199

public class KboatNoZero
{
    public void display() {
        
        int count = 0;
        for (int i = 100; i <= 200; i++) {
            
            boolean isNoZero = true;
            int t = i;
            while (t > 0) {
                if (t % 10 == 0) {
                    isNoZero = false;
                    break;
                }
                
                t /= 10;
            }
            
            if (isNoZero) {
                System.out.print(i + " ");
                count++;
            }
            
            //This will print 10 numbers per line
            if (count == 10) {
                System.out.println();
                count = 0;
            }
        }
        
    }
}
Output
BlueJ output of KboatNoZero.java

Question 4

Write a program to display all prime palindrome numbers between 10 and 1000.
[Hint: A number which is prime as well a palindrome is said to be 'Prime Palindrome' number.]
For example: 11, 101, 131, 151,

public class KboatPrimePalindrome
{
    public void displayPrimePalindrome() {

        int count = 0;

        for (int i = 10; i <= 1000; i++) {

            int num = i, revNum = 0;
            while (num != 0) {
                int digit = num % 10;
                num /= 10;
                revNum = revNum * 10 + digit;
            }


            if (revNum == i) {
                boolean isPrime = true;
                for (int j = 2; j <= i / 2; j++) {

                    if (i % j == 0) {
                        isPrime = false;
                        break;
                    }

                }
                if (isPrime) {
                    System.out.print(i + " ");
                    count++;
                    if (count == 10) {
                        System.out.println();
                        count = 0;
                    }
                }
            }
        }
    }
}
Output
BlueJ output of KboatPrimePalindrome.java

Question 5

In an entrance examination, students have been appeared in English, Maths and Science papers. Write a program to calculate and display average marks obtained by all the students. Take number of students appeared and marks obtained in all three subjects by every student along with the name as inputs.
Display the name, marks obtained in three subjects and the average of all the students.

import java.util.Scanner;

public class KboatStudentMarks
{
    public void studentMarks() {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter number of students: ");
        int studentCount = in.nextInt();
        
        String names[] = new String[studentCount];
        int engMarks[] = new int[studentCount];
        int sciMarks[] = new int[studentCount];
        int mathsMarks[] = new int[studentCount];
        double avgMarks[] = new double[studentCount];
        double totalMarks = 0.0;
        
        for (int i = 0; i < studentCount; i++) {
            System.out.println("Enter details of student " + (i + 1));
            System.out.print("Name: ");
            in.nextLine();
            names[i] = in.nextLine();
            System.out.print("Marks in English: ");
            engMarks[i] = in.nextInt();
            System.out.print("Marks in Science: ");
            sciMarks[i] = in.nextInt();
            System.out.print("Marks in Maths: ");
            mathsMarks[i] = in.nextInt();
            avgMarks[i] = (engMarks[i] + sciMarks[i] + mathsMarks[i]) / 3.0;
            totalMarks += avgMarks[i];
        }
        
        System.out.println();
        
        for (int i = 0; i < studentCount; i++) {
            System.out.println("Details of student " + (i + 1));
            System.out.println("Name: " + names[i]);
            System.out.println("English: " + engMarks[i]);
            System.out.println("Science: " + sciMarks[i]);
            System.out.println("Maths: " + mathsMarks[i]);
            System.out.println("Average: " + avgMarks[i]);
        }
        
        double classAvg = totalMarks / studentCount;
        System.out.println("\nAverage of all students is " + classAvg);
    }
}
Output
BlueJ output of KboatStudentMarks.java

Question 6

Write a program in Java to enter a number containing three digits or more. Arrange the digits of the entered number in ascending order and display the result.
Sample Input: Enter a number 4972
Sample Output: 2, 4, 7, 9

import java.util.Scanner;

public class KboatDigitSort
{
    public void sortDigits() {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a number having 3 or more digits: ");
        int OrgNum = in.nextInt();
        
        for (int i = 0; i <= 9; i++) {
            int num = OrgNum;
            int c = 0;
            while (num != 0) {
                if (num % 10 == i)
                    c++;
                num /= 10;
            }
            for (int j = 1; j <= c; j++) {
                System.out.print(i + ", ");
            }
        }
        
        System.out.println();
    }
}
Output
BlueJ output of KboatDigitSort.java

Question 7

Write a program to input a number and check whether it is 'Magic Number' or not. Display the message accordingly.
A number is said to be a magic number if the eventual sum of digits of the number is one.
Sample Input : 55
Then, 5 + 5 = 10, 1 + 0 = 1
Sample Output: Hence, 55 is a Magic Number.
Similarly, 289 is a Magic Number.

import java.util.Scanner;

public class KboatMagicNum
{

    public static void main(String args[]) {

        Scanner in = new Scanner(System.in);
        System.out.print("Enter number to check: ");
        int num = in.nextInt();
        int n = num;

        while (n > 9) {
            int sum = 0;
            while (n != 0) {
                int d = n % 10;
                n /= 10;
                sum += d;
            }
            n = sum;
        }

        if (n == 1)
            System.out.println(num + " is Magic Number");
        else
            System.out.println(num + " is not Magic Number");

    }
}
Output
BlueJ output of KboatMagicNum.java

Question 8

A number is said to be Multiple Harshad number, when divided by the sum of its digits, produces another 'Harshad Number'. Write a program to input a number and check whether it is a Multiple Harshad Number or not.
(When a number is divisible by the sum of its digit, it is called 'Harshad Number').
Sample Input: 6804
Hint: 6804 ⇒ 6+8+0+4 = 18 ⇒ 6804/18 = 378
378 ⇒ 3+7+8= 18 ⇒ 378/18 = 21
21 ⇒ 2+1 = 3 ⇒ 21/3 = 7
Sample Output: Multiple Harshad Number

import java.util.Scanner;

public class KboatMultipleHarshad
{
    public void checkMultipleHarshad() {
        
        Scanner in = new Scanner(System.in);
        System.out.print("Enter number to check: ");
        int num = in.nextInt();
        int dividend = num;
        int divisor;
        int count = 0;
        
        while (dividend > 1) {
            divisor=0;
            int t = dividend;
            while (t > 0) {
                int d = t % 10;
                divisor += d;
                t /= 10;
            }
            
            if (dividend % divisor == 0 && divisor != 1) {
                dividend = dividend / divisor;
                count++;
            }
            else {
                break;
            }
        }
        
        if (dividend == 1 && count > 1)
            System.out.println(num + " is Multiple Harshad Number");
        else
            System.out.println(num + " is not Multiple Harshad Number");
    }
}
Output
BlueJ output of KboatMultipleHarshad.java

Question 9

Write the programs to display the following patterns:

(a)

1
3 1
5 3 1
7 5 3 1
9 7 5 3 1

public class KboatPattern
{
    public void displayPattern() {
        for (int i = 1; i < 10; i = i + 2) {
            for (int j = i; j > 0; j = j - 2) {
                System.out.print(j + " ");
            }
            System.out.println();
        }
    }
}
Output
BlueJ output of KboatPattern.java

(b)

1   2   3   4   5
6   7   8   9
10 11 12
13 14
15

public class KboatPattern
{
    public void displayPattern() {
        int a = 1;
        for (int i = 5; i > 0; i--) {
            for (int j = 1; j <= i; j++) {
                System.out.print(a++ + "\t");
            }
            System.out.println();
        }
    }
}
Output
BlueJ output of KboatPattern.java

(c)

15 14 13 12 11
10 9 8 7
6 5 4
3 2
1

public class KboatPattern
{
    public void displayPattern() {
        int a = 15;
        for (int i = 5; i > 0; i--) {
            for (int j = 1; j <= i; j++) {
                System.out.print(a-- + "\t");
            }
            System.out.println();
        }
    }
}
Output
BlueJ output of KboatPattern.java

(d)

1
1 0
1 0 1
1 0 1 0
1 0 1 0 1

public class KboatPattern
{
    public void displayPattern() {
        int a = 1, b = 0;
        for (int i = 1; i <= 5; i++) {
            for (int j = 1; j <= i; j++) {
                if (j % 2 == 0)
                    System.out.print(b + " ");
                else
                    System.out.print(a + " ");
            }
            System.out.println();
        }
    }
}
Output
BlueJ output of KboatPattern.java

(e)

5 5 5 5 5
   4 4 4 4
      3 3 3
         2 2
            1

public class KboatPattern
{
    public void displayPattern() {
        for (int i = 0; i < 5; i++) {
            
            for (int j = i; j > 0; j--) {
                System.out.print("  ");
            }
            
            for (int k = 5 - i; k > 0; k--) {
                System.out.print((5 - i) + " ");
            }
            
            System.out.println();
        }
    }
}
Output
BlueJ output of KboatPattern.java

(f)

1 2 3 4 5
2 2 3 4 5
3 3 3 4 5
4 4 4 4 5
5 5 5 5 5

public class KboatPattern
{
    public void displayPattern() {
        for (int i = 1; i <= 5; i++) {
            
            for (int j = 1; j < i; j++)
                System.out.print(i + " ");
                
            for (int k = i; k <= 5; k++)
                System.out.print(k + " ");
                
            System.out.println();
        }
    }
}
Output
BlueJ output of KboatPattern.java

(g)

*
* #
* # *
* # * #
* # * # *

public class KboatPattern
{
    public void displayPattern() {
        for (int i = 1; i <= 5; i++) {
            for (int j = 1; j <= i; j++) {
                if (j % 2 == 0)
                    System.out.print("# ");
                else
                    System.out.print("* ");
            }
            System.out.println();
        }
    }
}
Output
BlueJ output of KboatPattern.java

(h)

5 4 3 2 1
5 4 3 2
5 4 3
5 4
5

public class KboatPattern
{
    public void displayPattern() {
        for (int i = 1; i <= 5; i++) {
            for (int j = 5; j >= i; j--) {
                System.out.print(j + " ");
            }
            System.out.println();
        }
    }
}
Output
BlueJ output of KboatPattern.java

(i)

1
2   3
4   5   6
7   8   9   10
11 12 13 14 15

public class KboatPattern
{
    public void displayPattern() {
        int a = 1;
        for (int i = 1; i <= 5; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print(a++ + "\t");
            }
            System.out.println();
        }
    }
}
Output
BlueJ output of KboatPattern.java

Question 10

Write a program to generate a triangle or an inverted triangle till n terms based upon the user's choice.

Example 1:
Input: Type 1 for a triangle and
Type 2 for an inverted triangle
Enter your choice 1
Enter the number of terms 5
Sample Output:
1
2 2
3 3 3
4 4 4 4
5 5 5 5 5

Example 2:
Input: Type 1 for a triangle and
Type 2 for an inverted triangle
Enter your choice 2
Enter the number of terms 6
Sample Output:
6 6 6 6 6 6
5 5 5 5 5
4 4 4 4
3 3 3
2 2
1

import java.util.Scanner;

public class KboatPattern
{
    public void choosePattern() {
        
        Scanner in = new Scanner(System.in);
        System.out.println("Type 1 for a triangle");
        System.out.println("Type 2 for an inverted triangle");
        
        System.out.print("Enter your choice: ");
        int ch = in.nextInt();
        
        System.out.print("Enter the number of terms: ");
        int n = in.nextInt();
        
        switch (ch) {
            case 1:
            for (int i = 1; i <= n; i++) {
                for (int j = 1; j <= i; j++) {
                    System.out.print(i + " ");
                }
                System.out.println();
            }
            break;
            
            case 2:
            for (int i = n; i > 0; i--) {
                for (int j = 1; j <= i; j++) {
                    System.out.print(i + " ");
                }
                System.out.println();
            }
            break;
            
            default:
            System.out.println("Incorrect Choice");
        }
    }
}
Output
BlueJ output of KboatPattern.java
BlueJ output of KboatPattern.java

Question 11

Using the switch statement, write a menu driven program for the following:

(a) To print the Floyd's triangle:
1
2   3
4   5   6
7   8   9   10
11 12 13 14 15

(b) To display the following pattern:
I
I C
I C S
I C S E

For an incorrect option, an appropriate error message should be displayed.

import java.util.Scanner;

public class KboatPattern
{
    public void choosePattern() {
        Scanner in = new Scanner(System.in);
        System.out.println("Type 1 for Floyd's triangle");
        System.out.println("Type 2 for an ICSE pattern");
        
        System.out.print("Enter your choice: ");
        int ch = in.nextInt();
        
        switch (ch) {
            case 1:
            int a = 1;
            for (int i = 1; i <= 5; i++) {
                for (int j = 1; j <= i; j++) {
                    System.out.print(a++ + "\t");
                }
                System.out.println();
            }
            break;
            
            case 2:
            String s = "ICSE";
            for (int i = 0; i < s.length(); i++) {
                for (int j = 0; j <= i; j++) {
                    System.out.print(s.charAt(j) + " ");
                }
                System.out.println();
            }
            break;
            
            default:
            System.out.println("Incorrect Choice");
        }
    }
}
Output
BlueJ output of KboatPattern.java
BlueJ output of KboatPattern.java

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