[Solved] Given the following tree, what does the optimized recursive DFS function return? Tree:... Given the following tree, what does the optimized recursive DFS function return? | Tree: Depth-First Search

Tree: Depth-First Search - Symmetric Tree (DFS Approach)

Given the following tree, what does the optimized recursive DFS function return? Tree: 1 / \ 2 2 / \ 3 3 Code snippet: ```python root = TreeNode(1, TreeNode(2, TreeNode(3)), TreeNode(2, None, TreeNode(3))) print(isSymmetric(root)) ```

ATrue

BDepends on tree height

CRaises an exception due to NoneType

DFalse

Step-by-Step Solution

Solution:

Step 1: Trace isMirror on root.left and root.right
Compare nodes with values 2 and 2: equal, continue.
Step 2: Compare left subtree's left (3) with right subtree's right (3) - equal; compare left subtree's right (None) with right subtree's left (None) - equal.
Both pairs match in value and structure.
Step 3: Check mirrored children of 3 nodes (both leaves) - both None, so symmetric at leaf level.
All mirrored pairs match, so tree is symmetric.
Final Answer:
Option A -> Option A
Quick Check:
Tree is symmetric due to matching structure and values [OK]

Quick Trick: Check mirrored children presence and values [OK]

Common Mistakes:

MISTAKES

Assuming same values mean asymmetric
Ignoring None node positions

Trap Explanation:

PITFALL

Candidates sometimes overlook mirrored None children matching causing incorrect asymmetry assumption.

Interviewer Note:

CONTEXT

Tests candidate's ability to trace recursion and handle None nodes

Master "Symmetric Tree (DFS Approach)" in Tree: Depth-First Search

3 interactive learning modes - each teaches the same concept differently

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More Tree: Depth-First Search Quizzes

Given the following tree, what does the optimized recursive DFS function return?

Step 1: Trace isMirror on root.left and root.right

Step 2: Compare left subtree's left (3) with right subtree's right (3) - equal; compare left subtree's right (None) with right subtree's left (None) - equal.

Step 3: Check mirrored children of 3 nodes (both leaves) - both None, so symmetric at leaf level.

Final Answer:

Quick Check:

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