How to convert a binary tree to binary search tree in-place, i.e., we cannot use any extra space

Question

How to convert a binary tree to binary search tree in-place, i.e., we cannot use any extra space.

Answer 1

Do the PostOrder Traversal and from that create a Binary search tree.

struct Node * newroot = '\0';

struct Node* PostOrder(Struct Node* root)
{
      if(root != '\0')
      {
          PostOrder(root->left);
          PostOrder(root->right);
          insertBST(root, &newroot);
      }
}

insertBST(struct Node* node, struct Node** root)
{
   struct Node * temp, *temp1;
   if( root == '\0')
   {
      *root == node;
       node->left ==  '\0';
       node->right == '\0';
   }
   else
   {
       temp = *root;
       while( temp != '\0')
       {
           temp1= temp;
           if( temp->data > node->data)
               temp = temp->left;
           else
               temp = temp->right;
       }
       if(temp1->data > node->data)
       {
           temp1->left = node;
       }
       else
       {
           temp1->right = node;
       }
       node->left = node->right = '\0';
    }
}