Snippets Algorithms
Algorithms
ShellSort Function
by: jayon crow
|
March 22, 2007
Version: 1.0
Type: Function
Category: Algorithms
License: GNU General Public License
Description: This is one of best sorting algorithm that use for sorting quickly . it's order is sqr(n)
/* Author: Masuod Maldar, masuod_maldar@yahoo.com
* UpdatedBy: J.B.Lamer, Date: 20070322
*
* It's like a binary bubble sort and is more consistant than quicksort
* and it's fast without creating other arrays or bins
*
* $array_to_sort is the array that needs sorting
* the keys are pulled and replaced with a normal numeric array
* false is returned if $array_to_sort is not an array
* and true is returned otherwise
*/
function shellsort( &$array_to_sort )
{
if ( !is_array($array_to_sort) )
{ return false; }
$array_to_sort = array_values($array_to_sort);
$len = count($array_to_sort);
$k = 0;
$gap[0] = floor( $len / 2 );
while ( $gap[$k] > 1 )
{
$k++;
$gap[$k] = floor($gap[$k-1]/2);
}
for ( $i=0; $i <= $k; $i++ )
{
$step = $gap[$i];
for ( $j = $step; $j < $len; $j++ )
{
$temp = $array_to_sort[$j];
$p = $j - $step;
while ( $p >= 0 && $temp < $array_to_sort[$p] )
{
$array_to_sort[$p+$step] = $array_to_sort[$p];
$p -= $step;
}
$array_to_sort[$p+$step] = $temp;
}
}
return true;
}
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