二叉树的先序，中序，后序遍历（非递归）和层序遍历

先序遍历：

void BTreePrevOrderNonR(BTNode* root)
{
	Stack s;
	StackInit(&s);
	BTNode* Top;
	BTNode* cur = root;
	while (cur || !StackEmpty(&s))
	{
		while (cur)
		{
			printf("%d ", cur->_data);
			StackPush(&s, cur);
			cur = cur->_left;
		}
		Top = StackTop(&s);
		StackPop(&s);
		cur = Top->_right;
	}
	printf("\n");
}void BTreePrevOrderNonR(BTNode* root)
{