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Consider the iterative approach to build a binary tree from preorder and inorder traversals. What is the output tree structure when preorder = [1] and inorder = [1]?

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Tree: Depth-First Search - Construct Tree from Preorder and Inorder
Consider the iterative approach to build a binary tree from preorder and inorder traversals. What is the output tree structure when preorder = [1] and inorder = [1]?
AA single node tree with value 1
BA tree with root 1 and a left child None
CNone (empty tree)
DA tree with root 1 and a right child None
Step-by-Step Solution
Solution:

  1. Step 1: Analyze input with single element

    Preorder and inorder both have one node, so root is created with value 1.

  2. Step 2: Check loop execution

    Since preorder has only one element, loop does not run, so no children are added.

  3. Final Answer:

    Option A -> Option A

  4. Quick Check:

    Single node tree with no children [OK]
Quick Trick: Single element preorder builds single node tree [OK]
Common Mistakes:
MISTAKES
  • Assuming empty tree or adding extra children
Trap Explanation:
PITFALL
  • Candidates may think no root is created or children are added incorrectly.
Interviewer Note:
CONTEXT
  • Tests handling of minimal edge case in iterative approach
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