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PHP Searching and Sorting Algorithm: Selection sort

PHP Searching and Sorting Algorithm: Exercise-4 with Solution

Write a PHP program to sort a list of elements using Selection sort.

The selection sort improves on the bubble sort by making only one exchange for every pass through the list.

Pictorial Presentation : Selection Sort

PHP sharp selection short

Sample Solution :

PHP Code :

<?php

function selection_sort($data)
{
for($i=0; $i<count($data)-1; $i++) {
	$min = $i;
	for($j=$i+1; $j<count($data); $j++) {
		if ($data[$j]<$data[$min]) {
			$min = $j;
		}
	}
    $data = swap_positions($data, $i, $min);
}
return $data;
}

function swap_positions($data1, $left, $right) {
	$backup_old_data_right_value = $data1[$right];
	$data1[$right] = $data1[$left];
	$data1[$left] = $backup_old_data_right_value;
	return $data1;
}
$my_array = array(3, 0, 2, 5, -1, 4, 1);
echo "Original Array :\n";
echo implode(', ',$my_array );
echo "\nSorted Array :\n";
echo implode(', ',selection_sort($my_array)). PHP_EOL;
?>

Sample Output:

Original Array :                                                    
3, 0, 2, 5, -1, 4, 1                                                
Sorted Array :                                                      
-1, 0, 1, 2, 3, 4, 5

Flowchart :

Flowchart: PHP - program of Selection sort

PHP Code Editor:

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Previous:Write a PHP program to sort a list of elements using Insertion sort.
Next: Write a PHP program to sort a list of elements using Shell sort.

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PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC