PHP Searching and Sorting Algorithm: Merge sort
PHP Searching and Sorting Algorithm: Exercise-17 with Solution
Write a PHP program to sort a list of elements using Merge sort.
According to Wikipedia "Merge sort (also commonly spelled mergesort) is an O (n log n) comparison-based sorting algorithm. Most implementations produce a stable sort, which means that the implementation preserves the input order of equal elements in the sorted output."
Pictorial presentation - Merge search algorithm :
Sample Solution :
PHP Code :
<?php
function merge_sort($my_array){
if(count($my_array) == 1 ) return $my_array;
$mid = count($my_array) / 2;
$left = array_slice($my_array, 0, $mid);
$right = array_slice($my_array, $mid);
$left = merge_sort($left);
$right = merge_sort($right);
return merge($left, $right);
}
function merge($left, $right){
$res = array();
while (count($left) > 0 && count($right) > 0){
if($left[0] > $right[0]){
$res[] = $right[0];
$right = array_slice($right , 1);
}else{
$res[] = $left[0];
$left = array_slice($left, 1);
}
}
while (count($left) > 0){
$res[] = $left[0];
$left = array_slice($left, 1);
}
while (count($right) > 0){
$res[] = $right[0];
$right = array_slice($right, 1);
}
return $res;
}
$test_array = array(100, 54, 7, 2, 5, 4, 1);
echo "Original Array : ";
echo implode(', ',$test_array );
echo "\nSorted Array :";
echo implode(', ',merge_sort($test_array))."\n";
?>
Sample Output:
Original Array : 100, 54, 7, 2, 5, 4, 1 Sorted Array : 1, 2, 4, 5, 7, 54, 100
Flowchart :

PHP Code Editor:
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PHP: Tips of the Day
$_COOKIE: This SuperGlobal Variable is used to retrieve Cookie value with given Key.
Example:
<?php $cookie_name = "data"; $cookie_value = "Foo Bar"; setcookie($cookie_name, $cookie_value, time() + (86400 * 30), "/"); if(!isset($_COOKIE[$cookie_name])) { echo "Cookie named '" . $cookie_name . "' is not set!"; } else { echo "Cookie '" . $cookie_name . "' is set!"; echo "\n"; echo "Value is: " . $_COOKIE[$cookie_value]; } ?>
Output:
Cookie named 'data' is not set!
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