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Chapter 3

Arrays

Class 10 - APC Understanding Computer Applications with BlueJ


Tick the correct answer

Question 1

Which of the following is the correct usage?

  1. int a[-40]
  2. int a[40]
  3. float a[0 - 40]
  4. None

Question 2

Which element is represented by a[10]?

  1. 10th
  2. 9th
  3. 11th
  4. None

Question 3

Cell numbers of a dimensional array are also known as:

  1. packets
  2. blocks
  3. subscripts
  4. compartments

Question 4

A dimensional array is also known as:

  1. subscripted variable
  2. actual variable
  3. compound variable
  4. none

Question 5

An array element can be accessed through:

  1. dots
  2. element name
  3. index number
  4. none

Question 6

Indicate the error message which displays, if the following statement is executed :
int a[5] = {28,32,45,68,12};

  1. Insufficient cells
  2. Array index out of bounce
  3. Elements exceeding cells
  4. None

Question 7

The following statement :
int code[ ]= {25,37,38,42};

  1. assigns 37 to code[1]
  2. assigns 25 to code[1]
  3. assigns 38 to code[3]
  4. assigns 42 to code[0]

Question 8

The elements of array[50] are numbered:

  1. from 1 to 50
  2. from 0 to 49
  3. from 1 to 51
  4. none

Question 9

Which of the following function finds the size of array
char m[] = {'R', 'A', 'J', 'E', 'N', 'D', 'R', 'A' };?

  1. m.size of (a)
  2. m.elements of (m)
  3. m.length
  4. None

Question 10

A Single Dimensional array contains N elements. What will be the last subscript?

  1. N-1
  2. N
  3. N+1
  4. None

Give the output of the following

Question 1

int m[] = {2,4,6,8};
System.out.println(m[1] + " " + m[2]);
Output
4 6
Explanation

m[1] gives the second element of the array which is 4
m[2] gives the third element of the array which is 6

Question 2

int a[] ={2,4,6,8,10};
a[0]=23;
a[3]=a[1];
int c= a[0]+a[1];
System.out.println("Sum = "+c);
Output
Sum = 27
Explanation

a[0]=23 assigns 23 to the first element of the array. a[3]=a[1] assigns the value of second element of the array which is 4 to the fourth element of the array. After the execution of these two statements array looks like this:
{23, 4, 6, 4, 10}
a[0]+a[1] ⇒ 23 + 4 ⇒ 27

Question 3

int a[]=new int [5]; 
a[0]=4; a[1]=8; a[2]=7; a[3]=12; a[4]=3; 
System.out.println(a[2+1]);
Output
12
Explanation

a[2+1] ⇒ a[3] ⇒ 12

Question 4

int a[4]={2,4,6,8};
for(i=0;i<=1;i++)
{
s=a[i]+a[3-i];
System.out.println(s);
}
Output
10
10
Explanation
iOutputRemark
0    a[0] + a[3]
⇒ 2 + 8
⇒10
First Iteration
1    a[1] + a[2]
⇒ 4 + 6
⇒10
Second Iteration

Write short answers

Question 1

What is meant by Dimensional Array?

A dimensional array is a structure created in the memory to represent a number of values of the same data type with the variables having the same variable name along with different subscripts.

Question 2

Name the two types of Dimensional Array.

  1. Single Dimensional Array
  2. Double Dimensional Array

Question 3

What is the need of Dimensional Array? Explain.

Variables are useful for keeping track of a single piece of information but as we collect more and more information, keeping the variables organized can be complicated. In such situations, we need arrays to solve the problems in a much better and efficient way.

Question 4

'Array is a composite data type'. Explain this statement.

The data type that represents a number of similar or different data under single declaration is called as composite data type. An array is a group or a collection of same type of variables. Hence, Array is a composite data type.

Question 5

Define the following with their constructs:

(a) Single Dimensional Array

A Single Dimensional Array contains one row and one or more columns. The syntax of declaring a Single Dimensional Array is:
<type> <array-variable>[] = new <type>[<size>];
OR
<type> [] <array-variable> = new <type>[<size>];

(b) Double Dimensional Array

Double Dimensional Array contains multiple rows and multiple columns. The syntax of declaring a Double Dimensional Array is:
<type> <array-variable>[][] = new <type>[<rows>][<columns>];
OR
<type> [][] <array-variable> = new <type>[<rows>][<columns>];

Differentiate between the following

Question 1

Subscript and Subscripted variable

Subscript is the index of the element in the array whereas Subscripted variable is the name of the array when it is used with a subscript to access a single element of the array.

Definitions of Subscript, Subscripted Variable, Subscripted Value in a Java array

Question 2

char a[5] and int a[5]

char a[5] is an array of char data type that can hold 5 characters whereas int a[5] is an array of int data type that can hold 5 integer values.

Question 3

Ordinary variable and array variable

An ordinary variable can hold only one value whereas an array variable can refer to a group of values of the same data type by using a subscript.

Question 4

Sorting and Searching

SortingSearching
Sorting means to arrange the elements of the array in ascending or descending order.Searching means to search for a term or value in an array.
Bubble sort and Selection sort are examples of sorting techniques.Linear search and Binary search are examples of search techniques.

Question 5

Linear search and Binary search

Linear SearchBinary Search
Linear search works on sorted and unsorted arraysBinary search works on only sorted arrays (ascending or descending)
Each element of the array is checked against the target value until the element is found or end of the array is reachedArray is successively divided into 2 halves and the target element is searched either in the first half or in the second half
Linear Search is slowerBinary Search is faster

Question 6

Selection sort and Bubble sort

Selection sortBubble sort
Selection Sort selects the smallest element from unsorted sub-array and swaps it with the leftmost unsorted element.Bubble Sort compares adjacent elements and swaps them if they are in wrong order.
Performs lesser number of swaps to sort the same array relative to Bubble SortPerforms more number of swaps to sort the array
Selection Sort is fasterBubble Sort is slower

Question 7

length and length()

lengthlength()
length is an attribute i.e. a data member of array.length() is a member method of String class.
It gives the length of an array i.e. the number of elements stored in an array.It gives the number of characters present in a string.

Solutions to Unsolved Java Programs

Question 1

Write a program in Java to store 20 numbers (even and odd numbers) in a Single Dimensional Array (SDA). Calculate and display the sum of all even numbers and all odd numbers separately.

import java.util.Scanner;

public class KboatSDAOddEvenSum
{
    public void displayOddEvenSum() {
        
        Scanner in = new Scanner(System.in);
        int arr[] = new int[20];
        
        System.out.println("Enter 20 numbers");
        for (int i = 0; i < arr.length; i++) {
            arr[i] = in.nextInt();
        }
        
        int oddSum = 0, evenSum = 0;
        
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] % 2 == 0)
                evenSum += arr[i];
            else
                oddSum += arr[i];
        }
        
        System.out.println("Sum of Odd numbers = " + oddSum);
        System.out.println("Sum of Even numbers = " + evenSum);
    }
}
Output
BlueJ output of KboatSDAOddEvenSum.java

Question 2

Write a program in Java to store 20 temperatures in °F in a Single Dimensional Array (SDA) and display all the temperatures after converting them into °C.
Hint: (c/5) = (f - 32) / 9

import java.util.Scanner;

public class KboatSDAF2C
{
    public void fahrenheit2Celsius() {
        Scanner in = new Scanner(System.in);
        double arr[] = new double[20];
        
        System.out.println("Enter 20 temperatures in degree Fahrenheit");
        for (int i = 0; i < arr.length; i++) {
            arr[i] = in.nextDouble();
        }
        
        System.out.println("Temperatures in degree Celsius");
        for (int i = 0; i < arr.length; i++) {
            double tc = 5 * ((arr[i] - 32) / 9);
            System.out.println(tc);
        }
    }
}
Output
BlueJ output of KboatSDAF2C.java

Question 3

Write a program in Java to store 10 numbers (including positive and negative numbers) in a Single Dimensional Array (SDA). Display all the negative numbers followed by the positive numbers without changing the order of the numbers.
Sample Input:

n[0]n[1]n[2]n[3]n[4]n[5]n[6]n[7]n[8]n[9]
1521-32-41546171-19-4452

Sample Output: -32, -41, -19, 44, 15, 21, 54, 61, 71, 52

import java.util.Scanner;

public class KboatSDANumbers
{
    public void displayNumbers() {
        Scanner in = new Scanner(System.in);
        int arr[] = new int[10];
        
        System.out.println("Enter 10 numbers");
        for (int i = 0; i < arr.length; i++) {
            arr[i] = in.nextInt();
        }
        
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] < 0)
                System.out.print(arr[i] + ", ");
        }
        
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] >= 0)
                System.out.print(arr[i] + ", ");
        }
    }
}
Output
BlueJ output of KboatSDANumbers.java

Question 4

Write a program in Java to store 20 numbers in a Single Dimensional Array (SDA). Display the numbers which are prime.
Sample Input:

n[0]n[1]n[2]n[3]n[4]n[5]...n[16]n[17]n[18]n[19]
456577719067...82193152

Sample Output: 71, 67, 19, 31

import java.util.Scanner;

public class KboatSDAPrimeNumbers
{
    public void displayPrimeNumbers() {
        Scanner in = new Scanner(System.in);
        int arr[] = new int[20];
        
        System.out.println("Enter 20 numbers");
        for (int i = 0; i < arr.length; i++) {
            arr[i] = in.nextInt();
        }
        
        System.out.println("Prime Numbers:");
        for (int i = 0; i < arr.length; i++) {
            
            if (arr[i] == 1)
                continue;
                
            boolean isPrime = true;
            for (int j = 2; j <= arr[i] / 2; j++) {
                if (arr[i] % j == 0) {
                    isPrime = false;
                    break;
                }  
            }
            
            if (isPrime)
                    System.out.print(arr[i] + ", ");
        }
    }
}
Output
BlueJ output of KboatSDAPrimeNumbers.java

Question 5

Write a program to accept name and total marks of N number of students in two single subscript arrays name[ ] and totalmarks[ ].
Calculate and print:
(i) The average of the total marks obtained by N number of students.
[average = (sum of total marks of all the students)/N]
(ii) Deviation of each student's total marks with the average.
[deviation = total marks of a student - average]

import java.util.Scanner;

public class KboatSDAMarks
{
    public void computeAvgNDev() {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter number of students: ");
        int n = in.nextInt();
        
        String name[] = new String[n];
        int totalmarks[] = new int[n];
        int grandTotal = 0;
        
        for (int i = 0; i < n; i++) {
            in.nextLine();
            System.out.print("Enter name of student " + (i+1) + ": ");
            name[i] = in.nextLine();
            System.out.print("Enter total marks of student " + (i+1) + ": ");
            totalmarks[i] = in.nextInt();
            grandTotal += totalmarks[i];
        }
        
        double avg = grandTotal / (double)n;
        System.out.println("Average = " + avg);
        
        for (int i = 0; i < n; i++) {
            System.out.println("Deviation for " + name[i] + " = " 
            + (totalmarks[i] - avg));
        }
    }
}
Output
BlueJ output of KboatSDAMarks.java

Question 6

The marks obtained by 50 students in a subject are tabulated as follows:-

NameMarks
..........
..........
..........

Write a program to input the names and marks of the students in the subject.
Calculate and display:
(a) The subject average marks (subject average marks = subject total/50).
(b) The highest marks in the subject and the name of the student. (The maximum marks in the subject are 100.)

import java.util.Scanner;

public class KboatSDAMarks
{
    public void computeAvgNHighestMarks() {
        final int TOTAL_STUDENTS = 50;
        Scanner in = new Scanner(System.in);
        
        String name[] = new String[TOTAL_STUDENTS];
        int marks[] = new int[TOTAL_STUDENTS];
        int total = 0;
        
        for (int i = 0; i < name.length; i++) {
            System.out.print("Enter name of student " + (i+1) + ": ");
            name[i] = in.nextLine();
            System.out.print("Enter marks of student " + (i+1) + ": ");
            marks[i] = in.nextInt();
            total += marks[i];
            in.nextLine();
        }
        
        double avg = (double)total / TOTAL_STUDENTS;
        System.out.println("Subject Average Marks = " + avg);
        int hIdx = 0;
        
        for (int i = 1; i < marks.length; i++) {
            if (marks[i] > marks[hIdx])
                hIdx = i;
        }
        
        System.out.println("Highest Marks = " + marks[hIdx]);
        System.out.println("Name = " + name[hIdx]);
    }
}
Output
BlueJ output of KboatSDAMarks.java

Question 7

Write a program in Java using arrays:
(a) To store the Roll No., Name and marks in six subjects for 100 students.
(b) Calculate the percentage of marks obtained by each candidate. The maximum marks in each subject are 100.
(c) Calculate the Grade as per the given criteria:

Percentage MarksGrade
From 80 to 100A
From 60 to 79B
From 40 to 59C
Less than 40D
import java.util.Scanner;

public class KboatSDAGrades
{
    public void computePercentageNGrade() {
        final int TOTAL_STUDENTS = 100;
        Scanner in = new Scanner(System.in);
        
        int rollNo[] = new int[TOTAL_STUDENTS];
        String name[] = new String[TOTAL_STUDENTS];
        int s1[] = new int[TOTAL_STUDENTS];
        int s2[] = new int[TOTAL_STUDENTS];
        int s3[] = new int[TOTAL_STUDENTS];
        int s4[] = new int[TOTAL_STUDENTS];
        int s5[] = new int[TOTAL_STUDENTS];
        int s6[] = new int[TOTAL_STUDENTS];
        double p[] = new double[TOTAL_STUDENTS];
        char g[] = new char[TOTAL_STUDENTS];
        
        for (int i = 0; i < TOTAL_STUDENTS; i++) {
            
            System.out.println("Enter student " + (i+1) + " details:");
            System.out.print("Roll No: ");
            rollNo[i] = in.nextInt();
            in.nextLine();
            System.out.print("Name: ");
            name[i] = in.nextLine();
            System.out.print("Subject 1 Marks: ");
            s1[i] = in.nextInt();
            System.out.print("Subject 2 Marks: ");
            s2[i] = in.nextInt();
            System.out.print("Subject 3 Marks: ");
            s3[i] = in.nextInt();
            System.out.print("Subject 4 Marks: ");
            s4[i] = in.nextInt();
            System.out.print("Subject 5 Marks: ");
            s5[i] = in.nextInt();
            System.out.print("Subject 6 Marks: ");
            s6[i] = in.nextInt();
            
            p[i] = (((s1[i] + s2[i] + s3[i] + s4[i] 
                    + s5[i] + s6[i]) / 600.0) * 100);
                    
            if (p[i] < 40)
                g[i] = 'D';
            else if (p[i] < 60)
                g[i] = 'C';
            else if (p[i] < 80)
                g[i] = 'B';
            else
                g[i] = 'A';
        }
        
        System.out.println();
        
        for (int i = 0; i < TOTAL_STUDENTS; i++) {
            System.out.println(rollNo[i] + "\t" 
                + name[i] + "\t" 
                + p[i] + "\t" 
                + g[i]);
        }
    }
}
Output
BlueJ output of KboatSDAGrades.java

Question 8

Write a program to accept a list of 20 integers. Sort the first 10 numbers in ascending order and next the 10 numbers in descending order by using 'Bubble Sort' technique. Finally, print the complete list of integers.

import java.util.Scanner;

public class KboatSDABubbleSort
{
    public void sortAscDsc() {
        Scanner in = new Scanner(System.in);
        int arr[] = new int[20];
        System.out.println("Enter 20 numbers:");

        for (int i = 0; i < arr.length; i++) {
            arr[i] = in.nextInt();
        }

        //Sort first half in ascending order
        for (int i = 0; i < arr.length / 2 - 1; i++) {
            for (int j = 0; j < arr.length / 2 - i - 1; j++) {
                if (arr[j] > arr[j + 1]) {
                    int t = arr[j + 1];
                    arr[j + 1] = arr[j];
                    arr[j] = t;
                }
            }  
        }

        //Sort second half in descending order
        for (int i = 0; i < arr.length / 2 - 1; i++) {
            for (int j = arr.length / 2; j < arr.length - i - 1; j++) {
                if (arr[j] < arr[j + 1]) {
                    int t = arr[j + 1];
                    arr[j + 1] = arr[j];
                    arr[j] = t;
                }
            }  
        }

        //Print the final sorted array
        System.out.println("\nSorted Array:");
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
    }
}
Output
BlueJ output of KboatSDABubbleSort.java

Question 9

The class teacher wants to store the marks obtained in English, Maths and Science of her class having 40 students. Write a program to input marks in Eng, Science and Maths by using three single dimensional arrays. Calculate and print the following information:
(i) Average marks secured by each student.
(ii) Class average in each subject.
[Hint: Class average is the average marks obtained by 40 students in a particular subject.]

import java.util.Scanner;

public class KboatSDAMarks
{
    public void computeStudentNClassAverage() {
        final int TOTAL_STUDENTS = 40;
        Scanner in = new Scanner(System.in);
        
        int english[] = new int[TOTAL_STUDENTS];
        int maths[] = new int[TOTAL_STUDENTS];
        int science[] = new int[TOTAL_STUDENTS];
        double avgMarks[] = new double[TOTAL_STUDENTS];
        
        for (int i = 0; i < TOTAL_STUDENTS; i++) {
            System.out.println("Enter student " + (i+1) + " details:");
            System.out.print("Marks in English: ");
            english[i] = in.nextInt();
            System.out.print("Marks in Maths: ");
            maths[i] = in.nextInt();
            System.out.print("Marks in Science: ");
            science[i] = in.nextInt();
            avgMarks[i] = (english[i] + maths[i] + science[i]) / 3.0;
        }
        
        int engTotal = 0, mathsTotal = 0, sciTotal = 0;
        
        for (int i = 0; i < TOTAL_STUDENTS; i++) {
            System.out.println("Average marks of student " + (i+1) + " = " + avgMarks[i]);
            engTotal += english[i];
            mathsTotal += maths[i];
            sciTotal += science[i];
        }
        
        System.out.println("Class Average in English = " + ((double)engTotal / TOTAL_STUDENTS));
        System.out.println("Class Average in Maths = " + ((double)mathsTotal / TOTAL_STUDENTS));
        System.out.println("Class Average in Science = " + ((double)sciTotal / TOTAL_STUDENTS));
    }
}
Output
BlueJ output of KboatSDAMarks.java
BlueJ output of KboatSDAMarks.java

Question 10

Write a program in Java to accept 20 numbers in a single dimensional array arr[20]. Transfer and store all the even numbers in an array even[ ] and all the odd numbers in another array odd[ ]. Finally, print the elements of both the arrays.

import java.util.Scanner;

public class KboatSDAEvenOdd
{
    public void segregateEvenOdd() {
        
        final int NUM_COUNT = 20;
        Scanner in = new Scanner(System.in);
        int i = 0;
        
        int arr[] = new int[NUM_COUNT];
        int even[] = new int[NUM_COUNT];
        int odd[] = new int[NUM_COUNT];
        
        System.out.println("Enter 20 numbers:");
        for (i = 0; i < NUM_COUNT; i++) {
            arr[i] = in.nextInt();
        }
        
        int eIdx = 0, oIdx = 0;
        for (i = 0; i < NUM_COUNT; i++) {
            if (arr[i] % 2 == 0)
                even[eIdx++] = arr[i];
            else
                odd[oIdx++] = arr[i];
        }
        
        System.out.println("Even Numbers:");
        for (i = 0; i < eIdx; i++) {
            System.out.print(even[i] + " ");
        }
        
        System.out.println("\nOdd Numbers:");
        for (i = 0; i < oIdx; i++) {
            System.out.print(odd[i] + " ");
        }
    }
}
Output
BlueJ output of KboatSDAEvenOdd.java

Question 11

Write a program to store 20 numbers in a Single Dimensional Array (SDA). Now, display only those numbers that are perfect squares.

n[0]n[1]n[2]n[3]n[4]n[5]...n[16]n[17]n[18]n[19]
124549786477...81994533

Sample Output: 49, 64, 81

import java.util.Scanner;

public class KboatSDASquares
{
    public void displayPerfectSquares() {
        Scanner in = new Scanner(System.in);
        int arr[] = new int[20];
        
        System.out.println("Enter 20 numbers");
        for (int i = 0; i < arr.length; i++) {
            arr[i] = in.nextInt();
        }
        
        System.out.println("Perfect Squares are:");
        for (int i = 0; i < arr.length; i++) {
            double sr = Math.sqrt(arr[i]);
            if ((sr - Math.floor(sr)) == 0)
                System.out.print(arr[i] + ", ");
        }
    }
}
Output
BlueJ output of KboatSDASquares.java

Question 12

To get promotion in a Science stream, a student must pass in English and should pass in any of the two subjects (i.e.; Physics, Chemistry or Maths). The passing mark in each subject is 35. Write a program in a Single Dimension Array to accept the roll numbers and marks secured in the subjects for all the students. The program should check and display the roll numbers along with a message whether "Promotion is Granted" or "Promotion is not Granted". Assume that there are 40 students in the class.

import java.util.Scanner;

public class KboatStudent
{
    public void computeResult() {
        
        Scanner in = new Scanner(System.in);
        int studentDetails[] = new int[200]; //40 * 5 = 200
        
        System.out.println("Enter student details");
        for (int i = 0, idx = 1; i < 200; i = i + 5, idx++) {
            System.out.print("Student " + idx + " roll number: ");
            studentDetails[i] = in.nextInt();
            System.out.print("Student " + idx + " English Marks: ");
            studentDetails[i+1] = in.nextInt();
            System.out.print("Student " + idx + " Maths Marks: ");
            studentDetails[i+2] = in.nextInt();
            System.out.print("Student " + idx + " Physics Marks: ");
            studentDetails[i+3] = in.nextInt();
            System.out.print("Student " + idx + " Chemistry Marks: ");
            studentDetails[i+4] = in.nextInt();
        }
        
        for (int i = 0; i < 200; i = i + 5) {
            System.out.println("Roll No: " + studentDetails[i]);
            if (studentDetails[i+1] > 34 && 
                ((studentDetails[i+2] > 34 && studentDetails[i+3] > 34) ||
                (studentDetails[i+2] > 34 && studentDetails[i+4] > 34) ||
                (studentDetails[i+3] > 34 && studentDetails[i+4] > 34))) {
                System.out.println("Promotion is granted.");
            }
            else {
                System.out.println("Promotion is not granted.");
            }
        }
    }
}
Output
BlueJ output of KboatStudent.java
BlueJ output of KboatStudent.java

Question 13

Write a program to accept 10 different decimal numbers (double data type) in a Single Dimensional Array (say, A). Truncate the fractional part of each number of the array A and store their integer part in another array (say, B).

import java.util.Scanner;

public class KboatSDATruncate
{
    public void truncateNumbers() {
        Scanner in = new Scanner(System.in);
        double a[] = new double[10];
        int b[] = new int[10];
        
        System.out.println("Enter 10 decimal numbers");
        for (int i = 0; i < a.length; i++) {
            a[i] = in.nextDouble();
            b[i] = (int)a[i];
        }
        
        System.out.println("Truncated numbers");
        for (int i = 0; i < b.length; i++) {
            System.out.print(b[i] + ", ");
        }
    }
}
Output
BlueJ output of KboatSDATruncate.java

Question 14

The annual examination result of 50 students in a class is tabulated in a Single Dimensional Array (SDA) is as follows:

Roll No.Subject ASubject BSubject C
............................
............................
............................

Write a program to read the data, calculate and display the following:
(a) Average marks obtained by each student.
(b) Print the roll number and the average marks of the students whose average is above. 80.
(c) Print the roll number and the average marks of the students whose average is below 40.

import java.util.Scanner;

public class KboatExamResult
{
    public void computeResult() {
        final int TOTAL_STUDENTS = 50;
        Scanner in = new Scanner(System.in);
        
        int rollNo[] = new int[TOTAL_STUDENTS];
        int sA[] = new int[TOTAL_STUDENTS];
        int sB[] = new int[TOTAL_STUDENTS];
        int sC[] = new int[TOTAL_STUDENTS];
        double avg[] = new double[TOTAL_STUDENTS];
        
        for (int i = 0; i < TOTAL_STUDENTS; i++) {
            System.out.println("Enter student " + (i+1) + " details:");
            System.out.print("Roll No: ");
            rollNo[i] = in.nextInt();
            System.out.print("Subject A Marks: ");
            sA[i] = in.nextInt();
            System.out.print("Subject B Marks: ");
            sB[i] = in.nextInt();
            System.out.print("Subject C Marks: ");
            sC[i] = in.nextInt();
            avg[i] = (sA[i] + sB[i] + sC[i]) / 3.0;
        }
        
        System.out.println("\nRoll No\tAverage Marks");
        for (int i = 0; i < TOTAL_STUDENTS; i++) {
            System.out.println(rollNo[i] + "\t" + avg[i]);
        }
        
        System.out.println("\nStudents with Average above 80:");
        for (int i = 0; i < TOTAL_STUDENTS; i++) {
            if (avg[i] > 80)
                System.out.println(rollNo[i] + "\t" + avg[i]);
        }
        
        System.out.println("\nStudents with Average below 40:");
        for (int i = 0; i < TOTAL_STUDENTS; i++) {
            if (avg[i] < 40)
                System.out.println(rollNo[i] + "\t" + avg[i]);
        }
    }
}
Output
BlueJ output of KboatExamResult.java
BlueJ output of KboatExamResult.java
BlueJ output of KboatExamResult.java

Question 15

Write a program to store 6 elements in an array P and 4 elements in an array Q. Now, produce a third array R, containing all the elements of array P and Q. Display the resultant array.

InputInputOutput
P[ ]Q[ ]R[ ]
4194
6236
171
282
3 3
10 10
  19
  23
  7
  8
import java.util.Scanner;

public class Kboat3Arrays
{
    public void copyArrays() {
        
        Scanner in = new Scanner(System.in);
        
        int P[] = new int[6];
        int Q[] = new int[4];
        int R[] = new int[10];
        int i = 0;
        
        System.out.println("Enter 6 elements of array P:");
        for (i = 0; i < P.length; i++) {
            P[i] = in.nextInt();
        }
        
        System.out.println("Enter 4 elements of array Q:");
        for (i = 0; i < Q.length; i++) {
            Q[i] = in.nextInt();
        }
        
        i = 0;
        while(i < P.length) {
            R[i] = P[i];
            i++;
        }
        
        int j = 0;
        while(j < Q.length) {
            R[i++] = Q[j++];
        }
        
        System.out.println("Elements of Array R:");
        for (i = 0; i < R.length; i++) {
            System.out.print(R[i] + " ");
        }
    }
}
Output
BlueJ output of Kboat3Arrays.java

Question 16

Write a program to accept the year of graduation from school as an integer value from the user. Using the binary search technique on the sorted array of integers given below, output the message "Record exists" if the value input is located in the array. If not, output the message "Record does not exist".
Sample Input:

n[0]n[1]n[2]n[3]n[4]n[5]n[6]n[7]n[8]n[9]
1982198719931996199920032006200720092010
import java.util.Scanner;

public class KboatGraduationYear
{
    public void searchGraduationYear() {
        Scanner in = new Scanner(System.in);
        int n[] = {1982, 1987, 1993, 1996, 1999, 2003, 2006, 2007, 2009, 2010};
        
        System.out.print("Enter graduation year to search: ");
        int year = in.nextInt();
        
        int l = 0, h = n.length - 1, idx = -1;
        while (l <= h) {
            int m = (l + h) / 2;
            if (n[m] == year) {
                idx = m;
                break;
            }
            else if (n[m] < year) {
                l = m + 1;
            }
            else {
                h = m - 1;
            }
        }
        
        if (idx == -1)
            System.out.println("Record does not exist");
        else
            System.out.println("Record exists");
    }
}
Output
BlueJ output of KboatGraduationYear.java

Question 17

Write a program to input and store roll numbers, names and marks in 3 subjects of n number of students in five single dimensional arrays and display the remark based on average marks as given below:

Average MarksRemark
85 — 100Excellent
75 — 84Distinction
60 — 74First Class
40 — 59Pass
Less than 40Poor
import java.util.Scanner;

public class KboatAvgMarks
{
    public void showRemark() {
        
        Scanner in = new Scanner(System.in);
        System.out.print("Enter number of students: ");
        int n = in.nextInt();
        
        int rollNo[] = new int[n];
        String name[] = new String[n];
        int s1[] = new int[n];
        int s2[] = new int[n];
        int s3[] = new int[n];
        double avg[] = new double[n];
        
        for (int i = 0; i < n; i++) {
            System.out.println("Enter student " + (i+1) + " details:");
            System.out.print("Roll No: ");
            rollNo[i] = in.nextInt();
            in.nextLine();
            System.out.print("Name: ");
            name[i] = in.nextLine();
            System.out.print("Subject 1 Marks: ");
            s1[i] = in.nextInt();
            System.out.print("Subject 2 Marks: ");
            s2[i] = in.nextInt();
            System.out.print("Subject 3 Marks: ");
            s3[i] = in.nextInt();
            avg[i] = (s1[i] + s2[i] + s3[i]) / 3.0;
        }
        
        System.out.println("Roll No\tName\tRemark");
        for (int i = 0; i < n; i++) {
            String remark;
            if (avg[i] < 40) 
                remark = "Poor";
            else if (avg[i] < 60)
                remark = "Pass";
            else if (avg[i] < 75)
                remark = "First Class";
            else if (avg[i] < 85)
                remark = "Distinction";
            else
                remark = "Excellent";
            System.out.println(rollNo[i] + "\t" 
                + name[i] + "\t" 
                + remark);
        }
    }
}
Output
BlueJ output of KboatAvgMarks.java
BlueJ output of KboatAvgMarks.java

Question 18

A double dimensional array is defined as N[4][4] to store numbers. Write a program to find the sum of all even numbers and product of all odd numbers of the elements stored in Double Dimensional Array (DDA).
Sample Input:

12 10 15 17
30 11 32 71
17 14 29 31
41 33 40 51

Sample Output:
Sum of all even numbers: ..........
Product of all odd numbers: ..........

import java.util.Scanner;

public class KboatDDAEvenOdd
{
    public void computeSumNProduct() {
        Scanner in = new Scanner(System.in);
        int N[][] = new int[4][4];
        long evenSum = 0, oddProd = 1;
        System.out.println("Enter the elements of 4x4 DDA: ");
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                N[i][j] = in.nextInt();
                if (N[i][j] % 2 == 0)
                    evenSum += N[i][j];
                else
                    oddProd *= N[i][j];
            }
        }
        
        System.out.println("Sum of all even numbers = " + evenSum);
        System.out.println("Product of all odd numbers = " + oddProd);
    }
}
Output
BlueJ output of KboatDDAEvenOdd.java

Question 19

A Departmental Shop has 5 stores and 6 departments. The monthly sale of the department is kept in the Double Dimensional Array (DDA) as m[5][6]. The Manager of the shop wants to know the total monthly sale of each store and each department at any time. Write a program to perform the given task.
(Hint: Number of stores as rows and Number of departments as columns.)

import java.util.Scanner;

public class KboatDepartmentalStore
{
    public void computeMonthlySale() {
        Scanner in = new Scanner(System.in);
        long m[][] = new long[5][6];
        
        for (int i = 0; i < 5; i++) {
            System.out.println("Store " + (i + 1) + " Sales");
            for (int j = 0; j < 6; j++) {
                System.out.print("Enter monthly sale of department " + 
                    (j + 1) + ": ");
                m[i][j] = in.nextInt();   
            }
        }
        
        System.out.println("\nMonthly Sale by store: ");
        for (int i = 0; i < 5; i++) {
            long storeSale = 0;
            for (int j = 0; j < 6; j++) {
                storeSale += m[i][j];
            }
            System.out.println("Store " + (i + 1) 
                + " Sales: " + storeSale);
        }
        
        System.out.println("\nMonthly Sale by Department: ");
        for (int i = 0; i < 6; i++) {
            long deptSale = 0;
            for (int j = 0; j < 5; j++) {
                deptSale += m[j][i];
            }
            System.out.println("Department " + (i + 1) 
                + " Sales: " + deptSale);
        }
    }
}
Output
BlueJ output of KboatDepartmentalStore.java
BlueJ output of KboatDepartmentalStore.java

Question 20

A Metropolitan Hotel has 5 floors and 10 rooms in each floor. The names of the visitors are entered in a Double Dimensional Array (DDA) as M[5][10].The Hotel Manager wants to know from the "Enquiry" about the position of a visitor (i.e. floor number and room number) as soon as he enters the name of the visitor. Write a program in Java to perform the above task.

import java.util.Scanner;

public class KboatHotelEnquiry
{
    public void hotelEnquiry() {
        Scanner in = new Scanner(System.in);
        String M[][] = new String[5][10];
        int i = 0, j = 0;
        
        for (i = 0; i < 5; i++) {
            System.out.println("Enter floor " + (i + 1) 
                + " guest details:");
            for (j = 0; j < 10; j++) {
                System.out.print("Guest in room " + 
                    (j + 1) + ": ");
                M[i][j] = in.nextLine();
            }
        }
        
        boolean found = false;
        System.out.print("\nEnter guest name to search: ");
        String guest = in.nextLine();
        for (i = 0; i < 5; i++) {
            for (j = 0; j < 10; j++) {
                if (M[i][j].equals(guest)) {
                    found = true;
                    break;
                }   
            }
            
            if (found)
                break;
        }
        
        if (found)
            System.out.println(guest + " is in room number "
                + (j + 1) + " on floor number " + (i + 1));
        else
            System.out.println(guest + 
                " is not staying at this hotel");
    }
}
Output
BlueJ output of KboatHotelEnquiry.java
BlueJ output of KboatHotelEnquiry.java

Question 21

A Class Teacher wants to keep the records of 40 students of her class along with their names and marks obtained in English, Hindi, Maths, Science and Computer Science in a Double Dimensional Array (DDA) as M[40][5]. When the teacher enters the name of a student as an input, the program must display the name, marks obtained in the 5 subjects and the total. Write a program in Java to perform the task.

import java.util.Scanner;

public class KboatDDAStudentRecord
{
    public void maintainRecords() {
        final int TOTAL_STUDENTS = 40;
        final int TOTAL_SUBJECTS = 5;
        final String SUBJECT_NAMES[] = {"English", "Hindi", 
            "Maths", "Science", "Computer Science"};
        Scanner in = new Scanner(System.in);
        String names[] = new String[TOTAL_STUDENTS];
        int marks[][] = new int[TOTAL_STUDENTS][TOTAL_SUBJECTS];
        int i = 0, j = 0;
        
        for (i = 0; i < TOTAL_STUDENTS; i++) {
            System.out.println("Student " + (i + 1) + " details:");
            System.out.print("Name: ");
            names[i] = in.nextLine();
            for (j = 0; j < TOTAL_SUBJECTS; j++) {
                System.out.print("Enter marks in " + 
                    SUBJECT_NAMES[j] + ": ");
                marks[i][j] = in.nextInt();   
            }
            in.nextLine();
        }
        
        System.out.print("\nEnter name of the student to search: ");
        String studentName = in.nextLine();
        for (i = 0; i < TOTAL_STUDENTS; i++) {
            if (names[i].equals(studentName))
                break;
        }
        
        if (i == TOTAL_STUDENTS) {
            System.out.println("Record for " + studentName 
                + " not found");
        }
        else {
            System.out.println("Name: " + names[i]);
            int total = 0;
            for (j = 0; j < TOTAL_SUBJECTS; j++) {
                System.out.println("Marks in " + 
                    SUBJECT_NAMES[j] + ": " + marks[i][j]);
                total += marks[i][j];
            }
            System.out.println("Total Marks: " + total);
        }
    }
}
Output
BlueJ output of KboatDDAStudentRecord.java

Question 22

If arrays M and M + N are as shown below, write a program in Java to find the array N.

M = {{-1, 0, 2},    M + N = {{-6, 9, 4},
     {-3, -1, 6},            {4, 5, 0},
     {4, 3, -1}}             {1, -2, -3}}
public class KboatSubtractDDA
{
    public void computeDiff() {
        
        int arrM[][] = {
            {-1, 0, 2},
            {-3, -1, 6},
            {4, 3, -1}
        };
        
        int arrSum[][] = {
            {-6, 9, 4},
            {4, 5, 0},
            {1, -2, -3}
        };
        
        int arrN[][] = new int[3][3];
        
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                arrN[i][j] = arrSum[i][j] - arrM[i][j];
            }
        }
        
        System.out.println("Array N:");
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                System.out.print(arrN[i][j]);
                System.out.print(' ');
            }
            System.out.println();
        }
    }
}
Output
BlueJ output of KboatSubtractDDA.java

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