Recover Binary Search Tree

#1

I am not able to solve this question. Please help.

#2

Approach

Here is the algorithm:

  1. Construct inorder traversal of the tree. It should be an almost sorted list where only two elements are swapped.
  2. Identify two swapped elements x and y in an almost sorted array in linear time.
  3. Traverse the tree again. Change value x to y and value y to x.

Complexity Analysis :

  • Time complexity : O(N). To compute inorder traversal takes O(N) time, to identify and to swap back swapped nodes O(1) in the best case and O(N) in the worst.
  • Space complexity : O(N) since we keep inorder traversal nums with N elements.

refer this --> https://ide.codingblocks.com/s/636876

#3

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