PHP Program to Count Sets of 1s and 0s in a Binary Matrix

<?php
// PHP program to compute number of sets
// in a binary matrix.

// Number of columns
$m = 3; 

// Number of rows
$n = 2; 

// Function to calculate the number 
// of non empty sets of cell
function countSets($a) { 
    global $m, $n;
    
    // Stores the final answer 
    $res = 0;
    
    // Traverses row-wise 
    for ($i = 0; $i < $n; $i++) {
        $u = 0; $v = 0; 
        for ( $j = 0; $j < $m; $j++) 
            $a[$i][$j] ? $u++ : $v++;     
        $res += pow(2, $u) - 1 + pow(2, $v) - 1; 
    } 
    
    // Traverses column wise 
    for ($i = 0; $i < $m; $i++) {
        $u = 0;$v = 0; 
        for ($j = 0; $j < $n; $j++) 
            $a[$j][$i] ? $u++ : $v++; 
        $res += pow(2, $u) - 1 + 
                pow(2, $v) - 1; 
    }
    
    // At the end subtract
    // n*m as no of single
    // sets have been added 
    // twice.
    return $res-($n*$m);
}

// Driver Code
$a = array(array(1, 0, 1),
           array(0, 1, 0));
    
echo countSets($a); 
    
?>