05c05-3.php

来自「介绍PHP5的给类型函数应用」· PHP 代码 · 共 54 行

<?php
// Implement the Shell Sort
function shell_sort(&$a) {
    $count = count($a);

    // Determine in our sequence of 2x + 1, what the highest value that is
    //  less than the count of the array is:
    $columns = 1;
    while ($columns < $count) {
        $columns = $columns * 2 + 1;
    }
    
    // Ok, Columns went one too far that way, so step back one
    $columns = ($columns - 1) / 2;
    // Now, as long as our number of columns to sort by is at LEAST 1
    while ($columns > 0) {
        // Loop for as many columns as we have:
        for ($c = 0; $c < $columns; $c++) {
            // Loop through all members of this column:
            for ($i = $columns; $i < $count; $i += $columns) {
                // Save the current value which we are going to compare:
                $value = $a[$i];
        
                // Loop backwards from the current value until we reach the
                //  start of the array or a value less than our current one
                for ($x = $i - $columns; 
                        ( ($x >= 0) && ($a[$x] > $value) ); 
                        $x -= $columns) {
                    // Swap this value down one place:
                    $a[$x + $columns] = $a[$x];
                }
        
                // Now assign our value to it's proper sorted position:
                $a[$x + $columns] = $value;
            }
        }

        // Now that we have finished with one set of columns
        //  reduce the number of columns:
        $columns = ($columns - 1) / 2;
    }
}
        
// Prepare an array of values:
$values = array(73, 3, 42, 6, 14, 23, 15, 9, 74, 1, 234, 45, 23, 76, 12, 3);

// Sort them:
shell_sort($values);

// Echo them out in order:
//  1 3 3 6 9 12 14 15 23 23 42 45 73 74 76 234
foreach ($values as $v) { echo "{$v} "; } 
?>