merge_sort.php

<?php

function merge_sort($my_array){
	echo "chamou merge_sort\n";
	if(count($my_array) == 1 ) {
		return $my_array;
	}
	
	$mid = count($my_array) / 2;
    
    $left = array_slice($my_array, 0, (int)$mid);
    $right = array_slice($my_array, (int)$mid);
	
	$left = merge_sort($left);
	$right = merge_sort($right);
	
	return merge($left, $right);
}

function merge($left, $right){
	echo "chamou merge\n";
	var_dump($left, $right);
	$res = array();
	$i = $j = 0;
	
	while ($i < count($left) && $j < count($right)){
		if($left[$i] < $right[$j]){
			$res[] = $left[$i];
			$i++;
		}else{
			$res[] = $right[$j];
			$j++;
		}
	}
	
	while ($i < count($left)){
		$res[] = $left[$i];
		$i++;
	}
	
	while ($j < count($right)){
		$res[] = $right[$j];
		$j++;
	}
	
	return $res;
}

$test_array = array(6, 5, 4, 3, 2, 1);

echo "Original Array : ";
echo implode(', ',$test_array );
echo "\nSorted Array :";
echo implode(', ',merge_sort($test_array))."\n";