编写算法判断该二叉树是否是一棵平衡二叉树。

bool IsAVL(BianryTreeNode* pRoot, int& height)
{
	if(pRoot == 0)
		return true;
	
	int leftHeight;
	bool leftResult = IsAVL(pRoot->left, leftHeight);
	int rightHeight;
	bool rightResult = IsAVL(pRoot->right, rightHeight);
	if(leftResult && rightResult && abs(leftHeight - rightHeight) <= 1)
	{
		height = max(leftHeight, rightHeight) + 1;
		return true;
	}
	else
	{
		height = max(leftHeight, rightHeight) + 1;
		return false;
	}
}