Quick Sort

gistfile1.php

<?php 
/*
 * QuickSort
 * &$a:リファレンス渡し
 * */
function quickSort(&$numArr,$left = 0,$right)
{
  //(1)
	if($left >= $right) {
		return;
	}
	//(2)
	swap($numArr,$left,ceil(($left+$right)/2));
	$last = $left;
	//(3)
	for($i = $left+1;$i<=$right;$i++) {
		if($numArr[$i] < $numArr[$left]) {
			swap($arrNum,++$last,$i);
		}	
	}
	//(4)
	swap($numArr,$left,$last);
	//(5)
	quickSort($numArr,$left,$last - 1);
	//(6)
	quickSort($numArr,$last + 1,$right);
}

function swap(&$numArr,$left,$right)
{
	$tmp = $numArr[$right];
	$numArr[$right] = $numArr[$left];
	$numArr[$left] = $tmp; 
}