二叉树转双向链表

void ConvertToList(TreeNode*& root) {  
  TreeNode* left;  
  TreeNode* right;  
  if (root) {  
    left = root->left_;  
    right = root->right_;  
    TreeNode* left_most_right = left;  
    while (left_most_right && left_most_right->right_) {  
      left_most_right = left_most_right->right_;  
    }  
    root->left_ = left_most_right;  
    if (left) {  
      ConvertToList(left);  
    }  
    if (left_most_right) {  
      left_most_right->right_ = root;  
    }  
    TreeNode* right_most_left = right;  
    while (right_most_left && right_most_left->left_) {  
      right_most_left = right_most_left->left_;  
    }  
    root->right_ = right_most_left;  
    if (right) {  
      ConvertToList(right);  
    }  
    if (right_most_left) {  
      right_most_left->left_ = root;  
    }  
  }  
} 

 1 void BiTreeToLinklist(BiTree &T)  // change tree to linklist
 2 {
 3     if(T != NULL) // 双向链表化
 4     {
 5         BiTreeToLinklist(T->lchild);
 6         T->lchild = pre;
 7         pre->rchild = T;
 8         pre = T;
 9         BiTreeToLinklist(T->rchild);
10     }
11 }