二叉树的前序、中序、后序线索化及遍历

void _PrevOrderThreading(Node *cur, Node *& prev)
{
if(cur == NULL)
{
return;
}

if(cur->_left == NULL)
{
cur->_leftTag == THREAD;
cur->_left = prev;
}
if(prev && prev->_right == NULL)
{
prev->_rightTag = THREAD;
prev->_right = cur;
}
prev = cur;
_PrevOrderThreading(cur->_left, prev);
_PrevOrderThreading(cur->right, prev);

}

void PrevOrderThd()
{
Node *cur = _root;
while(cur)
{
while(cur->_leftTag == LINK)
{
cout << cur->_data << " ";
cur = cur->_left;
}
cout << cur->_data << " ";

cur = cur->right;

//
//      while(cur->_rightTag == THREAD)
//      {
//          cur = cur->_right;
//          cout << cur->_data << " ";
//      }
//      if(cur->_leftTag == LINK)
//      {
//          cur = cur->_left;
//      }
//      else
//      {
//          cur = cur->_right;
//      }

}
}

void _InOrderThreading(Node *cur, Node *& prev)
{
if(cur == NULL)
{
return;
}
_InOrderThreading(cur->_left, prev);
//线索化
if(cur->_left == NULL)
{
cur->_leftTag = THREAD;
cur->_left = prev;
}
if(prev && prev->_right == NULL)
{
prev->_rightTag = THREAD;
prev->_right = cur;
}
prev = cur;
_InOrderThreading(cur->_right, prev);
}

void InOrderThd()
{
Node *cur = _root;
while(cur)
{
//找最左节点
while(cur->_leftTag == LINK)
{
cur = cur->_left;
}
cout << cur->_data << " ";
//访问连续后继
while(cur->_rightTag == THREAD)
{
cur = cur->_right;
cout << cur->_data << " ";
}
cur = cur->_right;
}
}

void _PostOrderThreading(Node *root, Node *&prev)
{
if (root == NULL)
{
return;
}
_PostOrderThreading(root->_LChild, prev);
_PostOrderThreading(root->_RChild, prev);
if (root->_LChild == NULL)
{
root->_LTag = THREAD;
root->_LChild = prev;
}
if (prev->_RChild == NULL)
{
prev->_RTag = THREAD;
prev->_RChild = root;
}
prev = root;
}

采用三叉链
或写一个查找根节点的方法