[Solved] Examine the following snippet from a House Robber III solution: ```python def dfs(node): if not node: return (0, 0) left = dfs(node.left) right = dfs(node.right) rob_current = node.... | Tree: Depth-First Search

Tree: Depth-First Search - House Robber III (On Tree)

Examine the following snippet from a House Robber III solution: ```python def dfs(node): if not node: return (0, 0) left = dfs(node.left) right = dfs(node.right) rob_current = node.val + left[0] + right[0] not_rob_current = max(left) + max(right) return (not_rob_current, rob_current) ``` Identify the subtle bug causing incorrect results.

ASwapping the order of returned tuple values causes confusion in parent calls

BUsing max(left) and max(right) instead of specific indices is incorrect

CAdding left[0] and right[0] to rob_current should be left[1] and right[1]

DReturning a tuple instead of a single integer causes type errors

Step-by-Step Solution

Solution:

Step 1: Understand returned tuple meaning
Conventionally, dfs returns (rob_current, not_rob_current) consistently.
Step 2: Check return order
This code returns (not_rob_current, rob_current), which is opposite of what callers expect.
Step 3: Consequence
Parent calls interpret values incorrectly, leading to wrong sums.
Final Answer:
Option A -> Option A
Quick Check:
Are return values consistent with usage? No. [OK]

Quick Trick: Return tuple order must match usage consistently [OK]

Common Mistakes:

MISTAKES

Mixing up tuple order of rob/not_rob values
Using max() on tuples instead of indices
Incorrectly summing child states

Trap Explanation:

PITFALL

Swapping tuple order looks harmless but breaks recursive logic.

Interviewer Note:

CONTEXT

Tests attention to detail in recursive state management.

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More Tree: Depth-First Search Quizzes

Examine the following snippet from a House Robber III solution: ```python def dfs(node): if not node: return (0, 0) left = dfs(node.left) right = dfs(node.right...

Step 1: Understand returned tuple meaning

Step 2: Check return order

Step 3: Consequence

Final Answer:

Quick Check:

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