Suppose the binary tree nodes can have duplicate values, and you are given preorder and inorder traversals with duplicates. Which approach best handles this variant?

hard🎤 Interviewer Follow-up Q10 of Q15

Tree: Depth-First Search - Construct Tree from Preorder and Inorder

AUse the standard hash map approach with value to index mapping

BUse iterative stack approach assuming unique values

CUse dynamic programming to memoize subtree constructions

DModify recursion to track indices ranges without relying on value-to-index map

Step-by-Step Solution

Solution:

Step 1: Understand duplicate value challenge
Hash maps with value keys fail because duplicates map to multiple indices.
Step 2: Modify recursion approach
Tracking index ranges without relying on value-to-index maps handles duplicates correctly.
Final Answer:
Option D -> Option D
Quick Check:
Index range tracking avoids hash map issues with duplicates [OK]

Quick Trick: Duplicates require index range tracking, not simple maps [OK]

Common Mistakes:

MISTAKES

Assuming unique values for all approaches

Trap Explanation:

PITFALL

Candidates try to reuse hash maps, failing on duplicates.

Interviewer Note:

CONTEXT

Tests advanced handling of duplicates in tree reconstruction

Master "Construct Tree from Preorder and Inorder" in Tree: Depth-First Search

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More Tree: Depth-First Search Quizzes

Suppose the binary tree nodes can have duplicate values, and you are given preorder and inorder traversals with duplicates. Which approach best handles this variant?

Step 1: Understand duplicate value challenge

Step 2: Modify recursion approach

Final Answer:

Quick Check:

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