Php Program to Sort the matrix row-wise and column-wise

Given a n x n matrix. The problem is to sort the matrix row-wise and column wise.
Examples:

Input : mat[][] = { {4, 1, 3},
                    {9, 6, 8},
                    {5, 2, 7} }
Output : 1 3 4
         2 5 7
         6 8 9

Input : mat[][] = { {12, 7, 1, 8},
                    {20, 9, 11, 2},
                    {15, 4, 5, 13},
                    {3, 18, 10, 6} } 
Output : 1 5 8 12
         2 6 10 15
         3 7 11 18
         4 9 13 20

Approach: Following are the steps:

1. Sort each row of the matrix.
2. Get transpose of the matrix.
3. Again sort each row of the matrix.
4. Again get transpose of the matrix.

Algorithm for getting transpose of the matrix:

for (int i = 0; i < n; i++) {
    for (int j = i + 1; i < n; i++) {
        int temp = mat[i][j];
        mat[i][j] = mat[j][i];
        mat[j][i] = temp;
    }
}

PHP

<?php
// PHP implementation to sort
// the matrix row-wise and
// column-wise
$MAX_SIZE = 10;

// function to sort each
// row of the matrix
function sortByRow(&$mat, $n)
{
    for ($i = 0; $i < $n; $i++)

        // sorting row number 'i'
        sort($mat[$i]);
}

// function to find
// transpose of the matrix
function transpose(&$mat, $n)
{
    for ($i = 0; $i < $n; $i++)
    {
        for ($j = $i + 1;
             $j < $n; $j++)
        {
            // swapping element at index (i, j)
            // by element at index (j, i)
            $t = $mat[$i][$j];
            $mat[$i][$j] = $mat[$j][$i];
            $mat[$j][$i] = $t;
        }
    }
}

// function to sort
// the matrix row-wise
// and column-wise
function sortMatRowAndColWise(&$mat, $n)
{
    // sort rows of mat[][]
    sortByRow($mat, $n);

    // get transpose of mat[][]
    transpose($mat, $n);

    // again sort rows of mat[][]
    sortByRow($mat, $n);

    // again get transpose of mat[][]
    transpose($mat, $n);
}

// function to print the matrix
function printMat(&$mat, $n)
{
    for ($i = 0; $i < $n; $i++)
    {
        for ($j = 0; $j < $n; $j++)
            echo $mat[$i][$j] . " ";
        echo "
";
    }
}

// Driver Code
$mat = array(array( 4, 1, 3 ),
             array( 9, 6, 8 ),
             array( 5, 2, 7 ));
$n = 3;

echo "Original Matrix:
";
printMat($mat, $n);

sortMatRowAndColWise($mat, $n);

echo "
Matrix After Sorting:
";
printMat($mat, $n);

// This code is contributed
// by ChitraNayal
?>

Output:

Original Matrix:
4 1 3
9 6 8
5 2 7

Matrix After Sorting:
1 3 4
2 5 7
6 8 9

Time Complexity: O(n²log₂n). 
Auxiliary Space: O(1).
Please refer complete article on Sort the matrix row-wise and column-wise for more details!