public class MatrixDemo {
public static void printMatrix(int[][] matrix) {
int rows = matrix.length; // number of rows
int cols = matrix[0].length; // number of columns
for (int i = 0; i < rows; i++) {
StringBuilder row = new StringBuilder();
for (int j = 0; j < cols; j++) {
// Pad each number to width 4
row.append(String.format("%4d", matrix[i][j]));
}
System.out.println(row);
}
}
public static void inverseMatrix(int[][] matrix) {
int rows = matrix.length;
int cols = matrix[0].length;
int counter = 0;
for (int i = 0, r = rows - 1; i < rows; i++, r--) {
for (int j = 0, c = cols - 1; j < cols; j++, c--) {
// swap values
int temp = matrix[i][j];
matrix[i][j] = matrix[r][c];
matrix[r][c] = temp;
counter++;
if (counter > (rows * cols) / 2 - 1) {
return;
}
}
}
}
public static void main(String[] args) {
int[][] matrix = {
{1, 2, 3, 4},
{5, 6, 7, 8},
{9, 10, 11, 12}
};
System.out.println("matrix:");
printMatrix(matrix);
inverseMatrix(matrix);
System.out.println("\ninverse matrix:");
printMatrix(matrix);
}
}
/*
run:
matrix:
1 2 3 4
5 6 7 8
9 10 11 12
inverse matrix:
12 11 10 9
8 7 6 5
4 3 2 1
*/
