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 inorder traversal of the binary tree and store the result. sort the result in acending order form the binary search tree by taking middle element of the sorted list as root( this can done using binary search). so we get balanced binary search tree.