55. Matrix Multiplication.

import java.util.Scanner;

class MatrixMultiplication
{
public static void main(String args[])
{
int m, n, p, q, sum = 0, c, d, k;

Scanner in = new Scanner(System.in);
System.out.println("Enter the number of rows and columns of first matrix");
m = in.nextInt();
n = in.nextInt();

int first[][] = new int[m][n];

System.out.println("Enter the elements of first matrix");

for (c = 0; c < m; c++)
{
for (d = 0; d < n; d++)
{
first[c][d] = in.nextInt();
}
}

System.out.println("Enter the number of rows and columns of second matrix");
p = in.nextInt();
q = in.nextInt();

if (n != p)
System.out.println("Matrices with entered orders can't be multiplied with each other.");
else
{
int second[][] = new int[p][q];
int multiply[][] = new int[m][q];

System.out.println("Enter the elements of second matrix");

for (c = 0; c < p; c++)
{
for (d = 0; d < q; d++)
{
second[c][d] = in.nextInt();
}
}

for (c = 0; c < m; c++)
{
for (d = 0; d < q; d++)
{
for (k = 0; k < p; k++)
{
sum = sum + first[c][k] * second[k][d];
}

multiply[c][d] = sum;
sum = 0;
}
}

System.out.println("Product of entered matrices:-");

for (c = 0; c < m; c++)
{
for (d = 0; d < q; d++)
{
System.out.print(multiply[c][d] + "\t");
}

System.out.print("\n");
}
}
}
}

@java_codings

56. Matrix Operations.

import java.util.Scanner;

public class Matrices {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

System.out.print("Enter number of rows: ");
int rows = scanner.nextInt();

System.out.print("Enter number of columns: ");
int columns = scanner.nextInt();

System.out.println();
System.out.println("Enter first matrix");
int[][] a = readMatrix(rows, columns);

System.out.println();
System.out.println("Enter second matrix");
int[][] b = readMatrix(rows, columns);

int[][] sum = add(a, b);
int[][] difference1 = subtract(a, b);
int[][] difference2 = subtract(b, a);

System.out.println();
System.out.println("A + B =");
printMatrix(sum);

System.out.println();
System.out.println("A - B =");
printMatrix(difference1);

System.out.println();
System.out.println("B - A =");
printMatrix(difference2);
}

public static int[][] readMatrix(int rows, int columns) {

int[][] result = new int[rows][columns];
Scanner s = new Scanner(System.in);

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

for (int j = 0; j < columns; j++) {

result[i][j] = s.nextInt();

}
}
return result;
}

public static int[][] add(int[][] a, int[][] b) {

int rows = a.length;
int columns = a[0].length;
int[][] result = new int[rows][columns];

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

for (int j = 0; j < columns; j++) {

result[i][j] = a[i][j] + b[i][j];

}
}
return result;
}

public static int[][] subtract(int[][] a, int[][] b) {

int rows = a.length;
int columns = a[0].length;
int[][] result = new int[rows][columns];

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

for (int j = 0; j < columns; j++) {

result[i][j] = a[i][j] - b[i][j];

}
}
return result;
}

public static void printMatrix(int[][] matrix) {

int rows = matrix.length;
int columns = matrix[0].length;

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

for (int j = 0; j < columns; j++) {

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

}
System.out.println();
}
}
}

@java_codings

57. Matrix Subtraction.

import java.util.Scanner;

class Matrix_Subtraction {

Scanner scan;
int matrix1[][], matrix2[][], sub[][];
int row, column;

void create() {

scan = new Scanner(System.in);

System.out.println("Matrix Subtraction");

// First Matrix Creation..
System.out.println("\nEnter number of rows & columns");
row = Integer.parseInt(scan.nextLine());
column = Integer.parseInt(scan.nextLine());

matrix1 = new int[row][column];
matrix2 = new int[row][column];
sub = new int[row][column];

System.out.println("Enter the data for first matrix :");

for(int i=0; i &lt row; i++) {

for(int j=0; j &lt column; j++) {

matrix1[i][j] = scan.nextInt();
}
}

// Second Matrix Creation..
System.out.println("Enter the data for second matrix :");

for(int i=0; i &lt row; i++) {

for(int j=0; j &lt column; j++) {

matrix2[i][j] = scan.nextInt();
}
}
}

void display() {

System.out.println("\nThe First Matrix is :");

for(int i=0; i &lt row; i++) {

for(int j=0; j &lt column; j++) {

System.out.print("\t" + matrix1[i][j]);
}
System.out.println();
}

System.out.println("\n\nThe Second Matrix is :");

for(int i=0; i &lt row; i++) {

for(int j=0; j &lt column; j++) {

System.out.print("\t" + matrix2[i][j]);
}
System.out.println();
}
}

void sub() {

for(int i=0; i &lt row; i++) {

for(int j=0; j &lt column; j++) {

sub[i][j] = matrix1[i][j] - matrix2[i][j];
}
}

System.out.println("\n\nThe Subtraction is :");

for(int i=0; i &lt row; i++) {

for(int j=0; j &lt column; j++) {

System.out.print("\t" + sub[i][j]);
}
System.out.println();
}
}
}

class MatrixSubtractionExample {

public static void main(String args[]) {

Matrix_Subtraction obj = new Matrix_Subtraction();

obj.create();
obj.display();
obj.sub();
}
}

@java_codings

58. Merge two array.

class MergeArrayDemo
{
public static void main(String args[])
{
Integer a[]={1,2,3,4};
Integer b[]={5,6,7,0};
Integer[] both = concat(a, b);

System.out.print("\nFirst Array : ");
for(int i=0;i<a.length;i++)
{
System.out.print(a[i]+"\t");
}

System.out.print("\nSecond Array : ");
for(int i=0;i<b.length;i++)
{
System.out.print(b[i]+"\t");
}

System.out.print("\nMerged Array : ");
for(int i=0;i<both.length;i++)
{
System.out.print(both[i]+"\t");
}
}

public static Integer[] concat(Integer[] a, Integer[] b)
{
int aLen = a.length;
int bLen = b.length;
Integer[] c= new Integer[aLen+bLen];
System.arraycopy(a, 0, c, 0, aLen);
System.arraycopy(b, 0, c, aLen, bLen);
return c;
}
}

@java_codings

59. Middle value of an array.

import java.util.*;

class MiddleValue
{
public static void main(String args[])
{
int[] a;
int i, j, n, sum = 0, swap, size;

double t;
Scanner sc = new Scanner(System.in);

System.out.println("Enter size of array");
size = sc.nextInt();

a = new int[size];

System.out.println("Enter numbers ");
for (i = 0; i < size; i++)
{
a[i] = sc.nextInt();
}

System.out.println("Numbers are : ");
for (i = 0; i < size; i++)
{
System.out.print(a[i] + " ");
}

//Sorting
for (i = 0; i < (size - 1); i++)
{
for (j = 0; j < (size - i - 1); j++)
{
if (a[j] > a[j + 1])
{
swap = a[j];
a[j] = a[j + 1];
a[j + 1] = swap;
}
}
}

System.out.println("\nNumbers in sorted order : ");
for (i = 0; i < size; i++)
{
System.out.print(a[i] + " ");
}

//Finding the Middle Value
if (size % 2 == 0)
{
n = (size + 1) / 2;
t = (a[n] + a[n - 1]) / 2.0;
System.out.println("\nMiddle Value is : " + t);
}

else
{
System.out.println("\nMiddle Value is : " + a[size / 2]);
}

}
}

@java_codings

60. Mirror Matrix.

import java.util.*;

class MirrorMatrix
{
public static void main(String[] args)
{
int row, column;
Scanner in = new Scanner(System.in);

System.out.print("Enter number of rows for matrix :");
row = in.nextInt();
System.out.print("Enter number of rows for matrix :");
column = in.nextInt();

int matrix[][] = new int[row][column];

System.out.println("Enter matrix : ");

for (int i = 0; i < row; i++)
{
for (int j = 0; j < column; j++)
{
matrix[i][j] = in.nextInt();
}
}

System.out.println("Mirror matrix : ");

for (int i = 0; i < row; i++)
{
for (int j = column - 1; j >= 0; j--)
{
System.out.print(matrix[i][j] + "\t");
}

System.out.println("");
}
}
}

@java_codings

61. Missing number in an array.

class MissingNumberArray
{
public static int count = 0;
public static int position = 0;
public static boolean flag = false;

public static void main(String[] args)
{
int a[] = {0, 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 20, 21, 23};

findMissingNumbers(a, position);
}

private static void findMissingNumbers(int a[], int position)
{
if (position == a.length - 1)
return;

for (; position < a[a.length - 1]; position++)
{
if ((a[position] - count) != position)
{
System.out.println("Missing Number: " + (position + count));
flag = true;
count++;
break;
}
}

if (flag)
{
flag = false;
findMissingNumbers(a, position);
}
}
}

@java_codings

62. Multidimensional Array.

class MultiDimArrayExample
{
public static void main(String[] args)
{
String[][] names = {{"Mr. ", "Mrs. ", "Ms. "}, {"Smith", "Jones"}};
// Mr. Smith
System.out.println(names[0][0] + names[1][0]);
// Ms. Jones
System.out.println(names[0][2] + names[1][1]);
}
}

@java_codings

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