输出所有可能的栈的合法出栈序列

void legalstack(tack* st, int in[], int out[], int len, int i, int j)
{
	int x;
	static int num = 1;
	if (empty(st) && j >= len)
	{
		cout << "第" << num++ << "种 : ";
		for (int i = 0; i < len; i++)
		{
			cout << out[i] << " ";
		}
		cout << endl;
	}
	else if (empty(st) == false && i < len)
	{
		x = gettop(st);
		pop(st);
		out[j] = x;
		legalstack(st, in, out, len, i, ++j);
		j--;
		push(st,x);

		push(st, in[i]);
		legalstack(st, in, out, len, ++i, j);
		i--;
		pop(st);
	}
	else if (empty(st) == false && i >= len)
	{
		x = gettop(st);
		pop(st);
		out[j] = x;
		legalstack(st, in, out, len, i, ++j);
		j--;
		push(st, x);
	}
	else if (empty(st) == true && i < len)
	{
		push(st, in[i]);
		legalstack(st, in, out, len, ++i, j);
		i--;
		pop(st);
	}
}