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
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($my_array)). PHP_EOL;
?>
Sample Output:
Original Array : 3, 0, 2, 5, -1, 4, 1 Sorted Array : -1, 0, 1, 2, 3, 4, 5
Flowchart :
PHP Code Editor:
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Previous:Write a PHP program to sort a list of elements using Insertion sort.
Next: Write a PHP program to sort a list of elements using Shell sort.
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PHP: Tips of the Day
How to Sort Multi-dimensional Array by Value?
Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:
Example:
function sortByOrder($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
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