GATE | GATE CS 2008 | Question 46
You are given the postorder traversal, P, of a binary search tree on the n elements 1, 2, …, n. You have to determine the unique binary search tree that has P as its postorder traversal. What is the time complexity of the most efficient algorithm for doing this?
(D) none of the above, as the tree cannot be uniquely determined.
Explanation: One important thing to note is, it is Binary Search Tree, not Binary Tree. In BST, inorder traversal can always be obtained by sorting all keys.
See method 2 of https://www.geeksforgeeks.org/construct-bst-from-given-preorder-traversa/ for details.
Same technique can be used for postorder traversal.
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