将二叉查找树转换为有序的双向链表

void Convert(BinaryTreeNode *pRoot, BinaryTreeNode *&pFirstNode, BinaryTreeNode *&pLastNode)
{
BinaryTreeNode *pFirstLeft, *pLastLeft; // 左子树转化为双向链表后的第一个、最后一个节点的指针
BinaryTreeNode *pFirstRight, *pLastRight; // 右子树转换为双向链表的第一个、最后一个节点的指针
if (pRoot == NULL) {
pFirstNode = NULL;
pLastNode = NULL;
}
if (pRoot->lchild == NULL) {
pFirstNode = pRoot;
}
else {
Convert(pRoot->lchild, pFirstLeft, pLastLeft);
pFirstNode = pFirstLeft;
pLastLeft->rchild = pRoot;
pRoot->lchild = pLastLeft;
}
if (pRoot->rchild == NULL) {
pLastNode = pRoot;
}
else {
Convert(pRoot->rchild, pFirstRight, pLastRight);
pLastNode = pLastRight;
pRoot->rchild = pFirstRight;
pFirstRight->lchild = pRoot;
}
}