[Solved] In the following code snippet for inverting a binary tree, which line causes the inversion to fail by not correctly swapping the children?def invertTree(node): if not node:... | Tree: Depth-First Search

Tree: Depth-First Search - Invert Binary Tree

In the following code snippet for inverting a binary tree, which line causes the inversion to fail by not correctly swapping the children?

def invertTree(node):
    if not node:
        return None
    invertTree(node.left)
    invertTree(node.right)
    node.left = node.right
    node.right = node.left
    return node

ALine 7: node.right = node.left

BLine 5: invertTree(node.right)

CLine 6: node.left = node.right

DLine 4: invertTree(node.left)

Step-by-Step Solution

Solution:

Step 1: Analyze swapping lines
Lines 6 and 7 attempt to swap children but overwrite values incorrectly.
Step 2: Identify bug
Line 7 assigns node.right = node.left after node.left was set to node.right, losing original left child.
Final Answer:
Option A -> Option A
Quick Check:
Swapping requires temporary variable [OK]

Quick Trick: Swapping without temp variable overwrites values [OK]

Common Mistakes:

MISTAKES

Ignoring need for temporary variable during swap
Assuming recursive calls fix swapping errors

Trap Explanation:

PITFALL

Overwriting node.right with node.left after node.left was changed loses original data.

Interviewer Note:

CONTEXT

Tests debugging skills and understanding of pointer swapping.

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More Tree: Depth-First Search Quizzes

In the following code snippet for inverting a binary tree, which line causes the inversion to fail by not correctly swapping the children?

Step 1: Analyze swapping lines

Step 2: Identify bug

Final Answer:

Quick Check:

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