递归反转一个栈

递归反转一个栈。要求空间复杂度为1，不许又一次申请一个相同的栈

算法思想：汉诺塔的思想

	function ReserveStack(&$stack){
		if(empty($stack)) return;
		$top = array_pop($stack);
		ReserveStack($stack);
		if(empty($stack)){
			array_push($stack,$top);
			return;
		}
		$top2 = array_pop($stack);
		ReserveStack($stack);
		array_push($stack,$top);
		ReserveStack($stack);
		array_push($stack,$top2);
	}
	
	$test = array(3,1,5,6,7,9,10,2);
	ReserveStack($test);
	print_r($test);