Finding the median of a column-wise sorted matrix

Here’s a Java program that solves the problem of finding the median of a column-wise sorted matrix:

  import java.util.Arrays;

   public class MedianOfSortedMatrix {

    public static double findMedian(int[][] matrix) {

        int rows = matrix.length;

        int columns = matrix[0].length;

        // Flattening the matrix into a 1D array

        int[] flattened = new int[rows * columns];

        int index = 0;

        for (int[] row : matrix) {

            for (int element : row) {

                flattened[index] = element;

                index++;

            }

        }

        // Sorting the flattened array

        Arrays.sort(flattened);

        // Finding the median

        if ((rows * columns) % 2 == 0) {

            int middleIndex1 = (rows * columns) / 2;

            int middleIndex2 = middleIndex1 - 1;

            return (flattened[middleIndex1] + flattened[middleIndex2]) / 2.0;

        } else {

            int middleIndex = (rows * columns) / 2;

            return flattened[middleIndex];

        }
    }

    public static void main(String[] args) {

        int[][] matrix = {

                {1, 3, 5},

                {2, 6, 9},

                {3, 6, 9}

        };

        double median = findMedian(matrix);

        System.out.println("Median: " + median);
    }
}

In this program, we first flatten the matrix into a 1D array by iterating over each element in the matrix. Then, we sort the flattened array in ascending order using `Arrays.sort()`. After that, we calculate the median based on the size of the flattened array.

In the `main` method, we create an example matrix and call the `findMedian` method to calculate the median. Finally, we print the result to the console.

Note: This program assumes that the matrix is column-wise sorted, meaning that each column is sorted in ascending order.